Car Seat Comparison: Cybex Sirona S and Sirona M

Car Seat Comparison: Cybex Sirona S and Sirona M

Coming at you today with another product comparison! Today we're dissecting the similarities and differences between the Cybex Sirona S and Sirona M Convertible Car Seats.

We'll break down their main differences in a minute, but first, let's talk about a few neat features that these car seats have in common.

SensorSafe Technology

Both the Sirona M and Sirona S convertible car seats from Cybex come equipped with SensorSafe Technology. Originally, Cybex developed it as a way to alert you if baby was left behind when you left your vehicle. If temperatures within the vehicle are changing drastically and become unsafe for baby or if your child unbuckles their chest clip while the vehicle is in motion, the sensor will alert you with the use of a receiver in your car's OBD port and a free app on your phone.

If for some reason you don't respond to the alerts after about 4-5 minutes, the receiver will notify your saved emergency contacts, as well as send them the location of the vehicle. I mean, come on! I feel that this is a feature that should be included on all car seats on the market. It's seriously cool!

Additional Features

Both car seats feature Linear Side Impact Protection or L.S.P., which is a bubble-like feature that pops out on the side of the car seat to reduce crash forces in a side impact collision.

They also each have magnetic harness holders to keep the harness out of the way when buckling your child. Both the Sirona M and Sirona S offer a 12-position height adjustable headrest that can easily be moved with one hand.

Sirona S Convertible Car Seat

Cybex's clever designs never cease to amaze me. What's so special about the Sirona S? It's the only convertible car seat in the U.S. that swivels 360 degrees to allow you to turn the seat toward your car door to easily buckle and unbuckle your child. Don't worry, the car seat locks automatically when weight is added so it cannot swivel while you are driving.

It's also the first American convertible car seat that features a load leg, a safety feature that helps stabilize the car seat in the event of a crash, which can be used in both rear and forward facing modes. In rear-facing mode, the base of the car seat serves as an anti-rebound panel against your vehicle seat to prevent movement ever further.

Installation is pretty slick too. Because of the unique 360 degree swivel, you may only need to install it one single time! The Sirona S can be used from birth-50 lbs rear-facing (which means you can safely keep your little one rear-facing for a long time!) and up to 65 lbs forward-facing. It has a 12-position recline to ensure your baby is comfortable and properly reclined for their age.

Both car seats give you a lot of bang for your buck! If you have more specific questions about these two car seats, feel free to reach out to our car seat experts!

You can shop both the Sirona M and Sirona S from Cybex in store or online at


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