Cybex Sirona S Review – Most Innovative Swivel Car Seat

CYBEX Sirona S 360° Rotating Car Seat

Cybex Sirona S

Overall Rating
Face Rear & Front

Usually, I like to highlight the top features but this time, I’m truly stumped. Not because this car seat has nothing going for it, but because it has everything going for it. The Cybex Sirona S is an absolute marvel in car seat innovation. It’s seen what its competitors can do and has savagely outpaced them with its innovative 360 degrees rotation, an adjustable load leg, and never-seen-before proprietary design and features. It’s the first 360 degree rotating car seat introduced from the EU to the US market, but still has a few great features that leave the competitors behind, like the SensorSafe technology. Let’s dive to explore more about the Cybex Sirona S car seat.

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Cybex Sirona S Review - Most Innovative Swivel Car Seat

Pros & Cons

The good and the bad

What is it best for

Who we recommend it for

Value for Money

Is it worth the price tag?


Dimensions, weight, color, etc

Safety Rating

Crash tests, FMVSS213, SIP


Weight/height limits, airplane, etc


Install with LATCH or seat belt


Other car seats to consider

1. Pros and Cons



2. Who Is It Best For?

Will the Cybex Sirona S Be a Good Fit For Your Child and Family?

Well, my first instinct is to say, every family.

That’s because the Sirona S has been built and designed according to the years of insights Cybex has received over the years they have been putting out car seats. As a result, everything this car seat offers is in response to a need vocalized by parents. 

It’s fully adaptable, thanks to its 360 degrees and a good size that is at the same level as other convertible car seats. This means it lasts good years while offering easy access to get the child in and out of the car seat for parents. We especially love the 50 lb rear-facing weight limit, which extended the rear-facing time for a longer safe ride.

Even as the first car seat that supports 360 degrees of rotation, the Cybex Sirona S still adds safety features into consideration. It includes a load leg to keep the seat stable while the built-in SensorSafe would work well to remind parents about the kid’s safe status in the car seat.

Along with a lot of innovative features in one car seat, it’s no surprise that the Cybex Sirona S is expensive. If you have fewer budget and want a swivel car seat that will last from your little one’s birth to youth, I’d recommend going with something with a higher size limit – and cheaper (like Evenflo Gold Revolve 360 or Graco Turn2Me) – before you spend over $500 on a convertible car seat for 4-5 years of use.

3. Value for Money

Is the price tag worth it?

Available on different e-commerce platforms, the Sirona S is, without any shadow of a doubt, one of the best value car seats I’ve ever reviewed. You only need to take a look at its impressive spec sheet and a long list of unique, proprietary features to see.

Investing in the Cybex Sirona S will secure you a car seat that has been entirely designed and manufactured on German soil. This might sound like a small detail but it’s unique to this model. Most car seats, including the Cybex’s successors, are a melting pot of standard elements you’d find in any component bin, put together in factories most commonly in a different country.

(Cybex was purchased by a Chinese company named Goodbaby in 2014.) This is why so many different models seem so similar, such as the car seats from Graco and Safety 1st

This isn’t the case with the Cybex Sirona S.

Everything about this car seat, from the two parts to its revolutionary 360-degree rotatable design, is unique to the car seat industry.

Of course, there are some successors following this design, like the Evenflo Revolve 360 and Nuna Revv, however, the Sirona S offers a more well-rounded package that a wider scope of parents would love. Plus, it’s a true masterclass in innovation, something that even your more impressive run-of-the-mill models lack.

But its 65 lb/49″ size limit is probably the biggest drawback for this innovative car seat with 360 degrees of spin. That being said, you’ll need another booster seat when your little one outgrows the car seat’s 65-pound weight limit or 49-inch height limit at around 5 years old.

Considering its high price of over $500, the Cybex Sirona S is not for all families who are on a tight budget.

If you’re going to shell out this much on a swivel car seat, there are only two other car seats you should consider alongside it, the Evenflo Gold Revolve360 and Graco Turn2Me.

4. Design

Dimensions and Width

Although the Cybex Sirona S isn’t as tank-like as some other all-in-one car seats, its prolonged depths from the front to the back – no matter in rear-facing or in forward-facing mode – certainly give its competitors a run for their money. Measuring 28.5-30 inches long, they almost rival those on the monstrous Britax One4Life, falling short by a mere half an inch.

As a rotating car seat, the Cybex Sirona S car seat has dimensions different for two directions for two modes: 

Rotating to rear-facing dimensions: 30″ L (D) x 21.5″ W x 23″ H

Rotating to forward-facing dimensions: 28.5″ L x 19″ W x 31″ H

The Sirona S is definitely not a compact car seat. It even needs more space in the back seat because of its rotating feature. That’s easy to understand. No matter which direction you want to rotate it, it will be always at a position and borrow space from the seat next to the installation spot.

It’s not a narrow profile car seat either. The narrowest 19-inch is good and acceptable for being slim fit as the best narrow car seats within 20-inch, but not as slim fit as those car seats that fit 3 across. However, this should be the second narrower among the rotating car seats, only beaten by the Nuna Revv’s 18.5-inch. 

If you’re planning to purchase it, it’s always important to measure your car’s interior dimensions and compare them to the dimensions of the Cybex Sirona S to ensure that it will fit properly. Additionally, if you have other passengers who will be riding in the back seat with the car seat installed, it’s important to consider how much space will be left for them.


Weighing 30.4 pounds, the Cybex Sirona S can’t claim to be the most lightweight of car seats, but it’s on a par with similar models. Saying that it’s around 11 to 12 lbs heavier than the traditional convertible car seats like the Graco Extend2Fit, although they lack the proprietary finesse that sets the Sirona S apart.

Because of its bulk, the Sirona S won’t be your first choice if you have a small car. There are lighter and cheaper models out there if you’re looking for something to travel with your kid. The Sirona S, on the other hand, can only be fully appreciated if you let it stay in one place and parents don’t need to switch the car seat often.

Heavy-duty shell means poor portability. So the Sirona S is not a good travel car seat. If you want a car seat with better portability like foldable or lightweight, rotating car seats including this one are not a perfect choice.

Check our post on the most portable car seats with lightweight and foldable models.

Two Cup Holders

The Sirona S is one of the car seats with cup holders. There are two included in the packing and they can be removable if getting dirty.

To attach and detach the cup holders, follow the instructions in the manual to put them in the accurate place indicated by a cup holder icon, which can be found on both sides.

Having the cup holders on the sides absolutely adds to the Sirona S’s overall width – it should be more than 19 inches after with two cup holders mounted on.

The two cup holders of Cybex Sirona S are obviously smaller than that of other swivel car seats. So the manufacturer offers a few tips in the car seat manual on how to use them safely.

Here list some:

ONLY use the cup holders that come with your original car seat or have been specifically designed for it by CYBEX.  DO NOT use the cup holder to hold hot liquids (e.g. coffee), even in enclosed or lidded containers. Placing hot liquids in the cup holder could result in spills and burn injuries to you or your child. 

• NEVER place sharp or pointed objects in the cup holder. In a crash these objects could hit you or your child and cause serious injuries. 

• ONLY use containers that fit securely all the way to the bottom of the cup holder. They should not stop halfway down when placing containers in the cup holder. 

• ONLY use containers with a capacity of 355 ml (12 oz.) or less. 

• NEVER use any containers which are made of brittle material (e.g., glass). This could lead to injuries in the event of a crash. 

• NEVER leave open containers in the cup holder during the journey. There is a risk of spilling (e.g., when braking), which may cause damage to the electrical components of the vehicle or seat upholstery. 

• ALWAYS remove containers before removing the cup holder from the car seat. 

• ALWAYS remove containers from the cup holder before reclining the car seat. There is a risk of spilling, which may cause damage to the electrical components of the vehicle or seat upholstery.

Headrest and Harness - 12 Positions

The Cybex Sirona S car seat has a 12-position height-adjustable headrest, which allows you to easily adjust the height of the headrest to fit your growing child.

This is important for keeping your little one comfortable in the car seat, as a properly fitting headrest can help to support your child’s head and neck, and can help to prevent slouching and discomfort during longer trips.

One lovely feature I think you would like is that you can adjust the headrest and harness with one hand. In addition to the 12-position headrest adjustment, the Sirona S also has a comfortable and supportive seat cushion, which is designed to help keep your child comfortable during road trips.

The seat cushion is made from a soft and breathable fabric and is ergonomically designed to support your child’s posture and provide a comfortable seating position.

Reclines - 12 Positions

The Cybex Sirona S car seat has 12 different recline positions, beating most car seats on the market. Parents can find and adjust the car seat to a perfect fit for growing children of different ages and sizes. 

In rear-facing, adjust reclines in the ‘blue’ zone; after switching to forward-facing mode, the reclines should be in the ‘red’ zone. 

The recline positions on the Sirona S can be adjusted easily using a lever located at the front of the seat, allowing you to find the most comfortable position for your child based on their age, size, and level of support needed. 

Headpad Insert and Newborn Insert

The Cybex Sirona S comes equipped with a few accessories for newborns – the headpad insert and newborn insert. They are designed to ensure a better fit for smaller infants, who may not fit well to reach the lowest harness slots.

Here are some tips to use the headpad insert and newborn insert.
ONLY USE the Newborn Insert and Newborn Headpad insert that comes with your original car seat or one that has been specifically designed for it by CYBEX.

Install Newborn Insert:
1. Pull Harness Buckle through slot in the bottom of Newborn Insert.
2. Pull both Harness Straps over the side panels of Newborn Insert.
3. Push Newborn Insert firmly into Child Restraint to make sure it is properly positioned.
4. When positioning the Headrest make sure the bottom of the Headrest flap is behind the Newborn Insert flap.

Install Newborn Head Insert
Tuck the tabs on the rear of the Newborn Headpad Insert them into the slots on the Headrest cover and toward the center of the Headrest.


The Cybex Sirona S car seat is designed with high-quality materials and padding to provide a comfortable and supportive seating experience for your child. The seat features a soft, breathable fabric that helps to keep your child cool and comfortable, no matter for daily pickups or long road trips.

Plus, the padding is made from energy-absorbing foam to provide extra protection for your child in the event of a crash. The headrest on the Sirona S is also well padded and designed to provide extra support and comfort for your child’s head and neck. The headrest can be adjusted to 10 different height positions, along with the 12-position reclines, ensuring that it can grow with your child and provide optimal support at all stages.

5. Crash Tests and Safety Ratings

Is it safe to use the Cybex Sirona S? 

Don’t worry about the Sirona S’s safety rating. It should rank top among the safe car seats. As the first rotating car seat introduced to the US market from the EU, it has been tested for safety using multiple crash test standards, including the European i-Size standard and the United States Federal Motor Vehicle Safety Standard (FMVSS) 213.

In Europe, the Sirona S is certified as an i-Size car seat, meaning it has been tested to meet rigorous safety standards for side-impact protection, as well as frontal impact protection. The i-Size standard also requires that car seats be tested for rear-facing use for up to at least 15 months. That’s easy to understand, rear-facing is considered safer for younger infants and toddlers than forward-facing positions.

In the United States, the Sirona S has passed the crash tests meeting the Federal Motor Vehicle Safety Standard (FMVSS 213). This standard includes tests for frontal impact, side-impact, and rollover crashes. The real fact is that all car seats sold in the US should be tested under this standard and approved for sale.

More than meeting these country-level mandatory standards, the Cybex Sirona S has also received high safety ratings from independent organizations. For example, the Sirona S has been awarded a “Best” rating from Consumer Reports for its performance in crash tests and ease of use. It has also received a “Good+” rating from the German consumer testing organization Stiftung Warentest.

Plus, the manufacturer also adds a few safety features for its protection performance, the SensorSafe technology, the load leg, and the anti-rebound design. Move on reading to the bonus features part.

Overall, the Cybex Sirona S has been rigorously tested for safety and has received high ratings from independent organizations, which can give parents peace of mind knowing that their child is protected while riding in the car.

Side Impact Protection

Most car seats (except the backless boosters and some high-back booster seats) have side impact protection. So does the Cybex Sirona S car seat. Different from the most common side-impact protection, the Sirona S features an adjustable Linear Side-Impact Protection (L.S.P.) system,  which can be extended on the side of the car seat closest to the door.

You can simply find it on both sides in the white lines area. This system helps to absorb the force of a side-impact crash and disseminate the crash energy away from your child’s head and body. The L.S.P. System can also be adjusted to fit different vehicles, and it can be easily moved out of the way when you are getting your child in and out of the car seat.

In addition to the L.S.P. System, the Sirona S also features energy-absorbing foam throughout the car seat to help protect your child’s head and torso, along with the reinforced steel frame for added durability and protection.

SensorSafe technology

The SensorSafe technology was a brilliant idea to add assurance to your child’s safety. Built into the chest clip of Sirona S (and other Cybex car seats), the SensorSafe clip helps send alerts about your kid’s safety and comfort status to your mobile app – it’s strongly recommended to download the Cybex app once you install the car seat in your vehicle.

What kinds of unsafe situations the SensorSafe would alert:

1. Reminder that your child is still in your automobile;

2. The little one unbuckles themselves;

3. The kid has been seated for too long (more than two hours);

4. The current temperature of your automobile interior (in the back seat where you place the car seat) is too warm or too cold.

The SensorSafe is useful at most times. However, if you’re taking the little one for a long road trip, they’ll probably stay more than 2 hours in the car seat. Another case is that if you live in a hot state or city like Florida, the temperature of the interior would be always higher than others, and you’ll keep receiving alerts. That would be annoying. It’s a pity that the manufacturer didn’t provide a solution for this case till now.

However, it seems the SensorSafe is helpful more than troublesome. The Evenflo has recently launched a new upgraded model with this technology as well.

Load Leg

The load leg attached to the car seat base is another excellent feature that is good to reduce the rotation in the event of a crash, increase the car seat stability, and finally enhance its protection.

To fit in various-sized vehicles, the Cybex designs the load leg to be adjustable. Here are some tips to use the load leg for Cybex Sirona S:

To Install:

1. Turn the base over and pull the Load Legout from the Storage Compartment.

2. Pull the Load Leg out until it CLICKS and is locked into the fully open position.

3. The Load Leg Indicator will turn GREENwhen locked.

To Extend:

Pull down on the Load Leg to extend the Foot until it rests on the vehicle floor.

NOTE: If the Load Leg does not reach the floor,squeeze the Load Leg Adjustment Button on the foot and pull down to further extend.As you lower the Load Leg, the Load Leg LockIndicator buttons on either side of the foot will show green as long as the Leg makes firm contact with the vehicle floor.

Secure the Foot into place using the first hole that will lock it firmly against the vehicle floor without lifting the Base up off of the seat.It may be necessary to lift up slightly on the Base to allow the Foot to lock into the hole.

To Retract:

Squeeze the Load Leg Adjustment Button and push up on the foot to retract it.

To Store:

1. Turn the Base over and rotate the Load Leg Towards the Storage Compartment.

2. Push the Load Leg in until it CLICKS and locks into the Storage Compartment. NOTE: If your child is over 40 pounds and riding forward-facing in an older vehicle with a lap belt only and no Tether Anchor,use the alternate storage position when storing the Load Leg.

There are very few car seats coming with a load leg. Besides this one, we only find the Nuna Pipa car seats (actually their bases) have a load leg as well.

Anti-rebound design

Similarly to the load leg, the anti-rebound works to reduce the wiggle of the car seat towards the rear of the vehicle. In this way, it helps enhance the protective performance in case of any crashes.

6. Performance

Weight and Height Limits

What are the height and weight limits for it?

The Cybex Sirona S car seat is designed to be used from birth up to 65 pounds, which is the maximum weight capacity for the car seat. That’s the average weight limit of convertible car seats. As the car seat is designed to be used in both rear-facing and forward-facing positions, we’ll explore more details on the rear-facing height and weight limit and forward-facing height and weight limit.

In the rear-facing position, the Sirona S can be used for newborns weighing as little as 4 pounds. This low weight requirement means it performs as good as most infant car seats. What we love the most is its rear-facing weight limit -it’s up to 50 pounds, making it one of the best rear-facing car seats 50 lbs

After switching to a forward-facing position, the car seat can be used for children weighing between 22 and 65 pounds. That’s the same as most convertible car seats, so does the height limit.

The Sirona S has a height limit of 49 inches for both rear-facing and forward-facing. If so, your kid should probably outgrow the 50-lb rear-facing weight limit first before they reach the 49-inch height limit, even though the manufacturer also indicates that the kid’s head must be at least one inch below the top of the headrest.

Stage / Modes

How many car seat stages will it go through?

The Cybex Sirona S car seat can be used in two different stages, which are the rear-facing stage and the forward-facing stage, according to the definition of NHTSA on the car seat stage.

The rear-facing stage is designed for newborns and small toddlers who weigh between 5 and 50 pounds, and who are less than 49 inches tall. The rear-facing stage is considered the safest way for younger kids to travel in a car, as it helps to protect their head, neck, and spine in the event of a crash.

After your child approaches or reaches the top weight limit (that’s the most probable case for Sirona S), typically around 2-3 years old, you should switch it to forward-facing. In this stage, the Sirona S is capable of accommodating children between 22 and 65 pounds, and who are less than 49 inches tall.

It is important to note that the American Academy of Pediatrics recommends keeping children in a rear-facing car seat for as long as possible, up to the weight and height limits of the car seat. As the car seat can be 360 degrees rotated, it’s much easier for parents to switch it from the first rear-facing stage to the second forward-facing stage.

Age Range

The Cybex Sirona S can be used for several years, thanks to its great 65 lbs/ 49″ size limit and a 10-year lifespan. Generally speaking, your kid might exceed the height or weight limit before it expires. So the age limit is mainly determined by the size limit.

In rear-facing, the 50-lb weight limit is the highest of 50+ car seats in our database, making Sirona S a good car seat to fit 2 years or older in this mode for a longer time. Small kids who grow at a slower pace than their peers, may still use this car seat at 3 or 4 years old.

The 65 lbs/ 49″ top size limit for forward-facing and overall makes the Sirona S a good car seat for 5 years old.


Is the Cybex Sirona S FAA approved for use on a plane?

No, the Cybex Sirona S car seat is NOT approved for use on an airplane. In the car seat manual, the manufacturer makes it clear that the car seat is NOT certified for aircraft use. 

It’s easy to understand this point. 

The car seat has two pieces – one base and one carrier shell, and most importantly, it’s rotatable. If you want to get the kid in and out of the car seat, it’s better to rotate it toward your side, but there should be no more space in a plane from the seat next to the car seat spot. Its heavy weight is another reason that we don’t recommend using the Sirona S on a plane. Taking a 30-pound tank-like car seat from home and passing the airports would be a big challenge for most families.

If you travel a lot, it’s better to get a car seat that is portable or lightweight for use. See our posts on the most portable car seats and lightweight convertible car seats. Also, there are some foldable car seats for easy carrying and storage. 

Actually, car seat weight is not the only factor. Diono Radian 3R weighs up to 25.9 pounds, but it’s also a good travel car seat for its folding design. You can fold the car seat up from the seat pad section and carry it like a backpack. 

But it is always a good idea to contact the airline in advance of your flight to confirm their policies regarding the use of car seats on the plane, and to ensure that you have all of the necessary equipment and information to secure the car seat safely.


How long is Cybex Sirona S good for

The lifespan of the Cybex Sirona S car seat is generally 10 years from the date of manufacture. This is in line with the recommended lifespan for most car seats, as materials can degrade and safety features can become less effective over time.

The date of manufacture can be found on a label affixed to the bottom of the child restraint. So it’s better to check this and record it before installing the car seat.

With knowing the date of manufacture and lifespan, you can calculate to get the exact expiration date. The car seat would work normally to provide promised protection before that date, if it was not used in any crashes before.

Tips: It’s the most common case that the kids outgrow the car seat before it’s expired, but you won’t be happy if you get a car seat that has been manufactured three or four years ago. You can check the date of manufacture for a car seat in the store, but if you’re planning to get one online via e-commerce platforms, it’s better to get one that is more popular. The more reviews it receives, the more popular it is.

See also:

Further Information

Car seat expiration tips

Warranty - Two Years

The Cybex Sirona S car seat comes with a limited warranty from the manufacturer. The specific details of the warranty may vary depending on the country or region in which you purchase the car seat. In the US, CYBEX warrants to the original consumer purchaser that this product will be free from defects in material and workmanship for two (2) years from the date of original purchase.

In general, the warranty for the Cybex Sirona S covers defects in materials or workmanship for a certain period of time from the date of purchase. During the Warranty Period, CYBEX, at its option, may repair or replace this product if it is found by the manufacturer to be defective in material or workmanship. CYBEX reserves the right to discontinue or change parts, fabrics, models, or products, or to substitute this product with a comparable model or product. 

It’s better to register the car seat at the very first time when you receive it and decide to keep it. Registering online at might be the most convenient way.

7. Cybex Sirona S Installation

Installing the Cybex Sirona S is a bit more difficult than other rotating car seats because of its additional load leg. You should make sure the load leg work correctly. 

You should always follow the manual to choose the safest place for installation.

Because it can be rotated, so you just need to install the car seat once if using the vehicle seat belt and twice if using the LATCH – there is a LATCH weight limit. That’s common for all car seats.

Installing Cybex Sirona S with Lap/Shoulder Belt

  • REAR-FACING: ALWAYS store Tether Strap when using REAR-FACING.
  • BEFORE installing the car seat, make sure the vehicle is on level ground. Place Restraint on approved vehicle seating location. MAKE SURE LATCH Connectors are stored.

1. Unfold the Load Leg from underneath the Base.

2. Position Restraint on rear vehicle seat. If a hump is present on vehicle floor, check the car seat manual for important information on the limits of using Load Leg in this seating position.

NOTE: If installing the car seat with the Load Leg stored, see Overhang Indicator in the manual as well.

3. Rotate Restraint REAR-FACING and move past the most upright position to access the Belt Path.

4. Remove Belt Path Cover from Base.

5. Open Belt Tensioner.

a. Pull EasyLock out and up to extend until you hear a CLICK.

b. Slide Lock Button and pull up to open Belt Tensioner in center of Base.

6. Pull out vehicle belt to form single length of about 60 cm (24 in). Hold Buckle Tongue in one hand and squeeze lap and shoulder belts together in other hand.

7. Route vehicle belts up through vehicle belt path opening on side of Base, through Belt Guide, under Belt Tensioner, through opposite Belt Guide, and down through opposite belt path opening. BUCKLE THE BELT. Make sure belts are underneath tabs on belt guide and lie flat without twisting.

NEVER place vehicle belt over Belt Tensioner, even in a vehicle with longer buckle stalks. This will prevent proper operation of the Child Restraint.

8. On buckle side, first lift up on shoulder belt to remove slack in lap belt. Then remove slack from shoulder belt on opposite side.

At this point, only remove slack from vehicle belts, being careful not to overtighten them.

Belt Tensioner will tighten system fully. If you have previously installed Restraint using LATCH, make sure LATCH Strap lies flat on bottom of the Base. See “To Store” section.

Some vehicle lap/shoulder belts have a plastic button or extra fold of webbing on the belt. Do not allow these to interfere with belt routing through Belt Tensioner. If they interfere:

a. Use LATCH if within the weight limit, or

b. Move the child restraint to a different location.

9. Close Belt Tensioner and use EasyLock to lock it into place.

a. Position EasyLock so that notches on arm rest on the tabs on either side of the Belt Tensioner.

b. Push down on EasyLock to close Belt Tensioner until it locks in place.

c. Store the EasyLock.

NOTE: If Belt Tensioner does not lock, try loosening lap/shoulder belt strap slightly.

10. Grab Base near belt path and pull side to side and front to back to make sure Base is installed tightly. Base should not move more than 2.5 cm (1 in) side to side or front to back at the Belt Path on the Child Restraint.

If Base moves too much, open Belt Tensioner, tension vehicle belt a little more and try again. After this, if Base still moves too much,

you may need to try a different vehicle seat location or installation method, or both. In most vehicles, you can switch shoulder belt retractor into locking mode by pulling out shoulder belt all the way and letting it rewind into the retractor. Pull on shoulder belt to make sure it is locking.

NEVER install this Child Restraint using a non-locking vehicle lap/shoulder belt.

NOTE: Refer to your vehicle Owner’s Manual for information.

11. Replace Belt Path Cover on Base, making sure to insert the tabs at the bottom corners of the cover into the Base before closing.

Belt Path Cover will close with an audible CLICK.

NOTE: To avoid interference with recline and rotation, ensure the Belt Path Cover is properly closed.

12. Move Restraint to the appropriate REAR FACING or FORWARD-FACING position based on the child’s size (pages 8-11) and lock into position.

Before moving the Restraint to the FORWARD-FACING position, you must first remove the Tether from the Tether Storage Compartment on the back of the Restraint.

a. Rotate the Restraint to the FORWARD FACING position.

b. Locate the vehicle Tether Anchor and attach the Tether Hook to the Tether Anchor.

c. Pull the Tether Adjuster Strap to tighten.

ALWAYS USE A TETHER FORWARD-FACING if a Tether Anchor is available. A Tether reduces the movement of FORWARD-FACING child restraint in a crash and helps to achieve a tight installation. Tether Anchor locations vary from vehicle to vehicle. Refer to your vehicle owner’s manual for exact locations, anchor identification, and requirements. Refer to page 51 for some common locations.

13. Extend Load Leg as the instructions in the car seat manual.

14. CHECK Recline Angle using Level Indicator.

For REAR-FACING installation, Recline Ball should be in BLUE ZONE.

For FORWARD-FACING installation, Recline Ball should be in RED ZONE.

15. Extend L.S.P. toward the vehicle door if in an outboard seating position in the car seat manual.

Cybex Sirona S Car Seat Manual

The user manual is the most important thing to use the car seat correctly. You should always read the user manual before starting to install and use it for riding your child. 

The Cybex Sirona S’s manual is stored in a small storage slot at the back of the car seat, but you can always find the online user manual on its official website, or download the PDF here.

8. Specification and Comparison

Suitable forNewborns, toddlers, and preschoolers
PositionsRear-facing and forward-facing
Portability (1-10)7. Bulky and heavy duty
Weight (lb.)30.4
Weight limit (lb.)4-50 (RF); 22-65 (FF)
Height limit (inch)49” (RF & FF)
Dimension30″L x 19 W x 24 H
Cup holderTwo
Age RangeBirth-4~5 years or older
Stage1st, 2nd
InstallationLATCH and seat belt
Headrest Positions12
Recline Positions12
Lifespan10 Years
Extra Features360-degree rotation, SensorSafe technology, load leg, anti-rebound

Cybex Sirona S vs other Car Seats

Check our best recommendations as alternatives to Cybex Sirona S. And here we also want to compare these car seats with detailed features so that you know why Sirona S outperforms or why its competitors stand out.

Cybex Sirona S vs Nuna Revv

Car Seats Comparison Nuna Revv Cybex Sirona S
Price $650 $549.99
Rotation 360 Degrees 360 Degrees
Weight limit (lb) RF:4-40 / FF: 25-40 RF:4-50 / FF: 22-65
Height limit (in) RF:43"* / FF: 43" RF:49"* / FF: 49"
Headrest Adjustable Positions 10 12
Reclines 10 12
Steel Reinforced
Cup Holder Two Two
Stages Rear-facing / Forward-Facing Rear-facing / Forward-Facing
Type Convertible Convertible
Side Impact Protection Aeroflex™ SIP system Linar SIP
Bonus Features FR-free material, anti-rebound bar SensorSafe technology, load leg, EasyLock bar, anti-rebound bar
Width 18.5" 19"

*About the 49″ height limit for rear-facing: The top of the head must be 1” (2.5 cm) below the headrest adjustment lever.

From the specs comparison, it seems the Cybex Sirona S winning over Nuna Revv. Actually, that’s also what we tell our readers – if you want to try to step into the rotating car seat world, the Sirona S would be a better choice than the Nuna Revv.

Cybex Sirona S vs Evenflo Revolve 360

Car Seats Comparison Evenflo Revolve 360 Cybex Sirona S
Price $399.99 $549.99
Rotation 360 Degrees 360 Degrees
Weight limit (lb) RF:4-40 / FF: 22-65/ Booster: 40-120 RF:4-50 / FF: 22-65
Height limit (in) RF:40"* / FF: 49"/ Booster: 57" RF:49"* / FF: 49"
Headrest Adjustable Positions 10 12
Reclines 4 12
Steel Reinforced
Cup Holder Two Two
Stages Rear-facing / Forward-Facing / Booster Rear-facing / Forward-Facing
Type All-in-one Convertible
Side Impact Protection Common SIP Adjustable Linar SIP
Bonus Features - SensorSafe technology, load leg, EasyLock bar, anti-rebound bar
Width 19.8" 19"

The Cybex Sirona S should be the most innovative rotating car seat now. It has a few additional safety features that make it stand out from most car seats on the market. Even our best recommendation – Evenflo Gold Revolve360 loses the competition compared to Cybex’s innovation. However, Evenflo Revolve 360 is always our No.1 choice if we need a rotating car seat.

9. Alternatives

What other swivel car seats should you consider?

Evenflo Gold Revolve360

Evenflo Gold Revolve 360

Why is it better than the Cybex Sirona S?
Why is it worse than the Cybex Sirona S?
Nuna REVV Rotating Convertible Car Seat

Nuna Revv

Why is it better than the Cybex Sirona S?
Why is it worse than the Cybex Sirona S?