CYBEX Sirona Si Rotating Toddler Car Seat with Integrated Base

CYBEX Sirona Si i-Size Rotating Rear-Facing Car Seat with Integrated ISOFIX Base

The CYBEX Sirona Si brings rear-facing safety at its very best to the new Platinum S-Line, with an integrated ISOFIX base built in. There’s no separate base or adapter to buy: simply install it in your car and it’s ready to go. This rotating i-Size car seat keeps your child safe and snug facing the rear from approx. 3 months up to 4.5 years (61–105 cm, max. 20 kg), or from birth with the optional newborn inlay. Approved to UN R129/04, it’s one of the most advanced extended rear-facing seats in our i-Size car seats range.

Choose Comfort or Style

The Sirona Si comes in two fabric finishes. Comfort is soft and practical, in Cozy Beige or Sepia Black. Style takes its cue from luxury car interiors, pairing two-tone leather-look accents with breathable 3D mesh that regulates moisture and boosts airflow by up to six times compared with conventional materials, and adds an XXL sun canopy. Style is available in Sepia Black, Amber Brown, Misty Grey, Opal Blue, Quartz Pink, Jade Green and Off White. Both versions offer exactly the same safety features, and every CYBEX fabric is screened for harmful substances such as heavy metals, phthalates and flame retardants.

Rear-facing safety for longer

Travelling rear-facing gives your child up to 50% better protection* in a frontal impact. The padded Sirona Si shell acts like a protective shield, spreading impact forces and holding your child close, while Linear Side-Impact Protection (L.S.P.) channels energy into the energy-absorbing shell and headrest for up to 25% more side-impact protection**. The integrated L.S.P. folds out with a simple push during setup and tucks neatly away when space is tight.

Grows with your child

CYBEX GrowTech is designed so the seat adapts as your child grows. The Comfort inlay is included and supports smaller children until they reach 85 cm. For use from day one, the Newborn insert and Newborn inlay are available as accessories for babies 40–60 cm. AGR-certified ergonomics, an adjustable headrest, a natural M-position and 40% more recline range than its predecessor*** keep your child comfortable whether they’re napping or watching the world go by.

One-handed rotation and easy boarding

Simply turn the seat towards the car door with one hand to lift your child in and out from the side, reducing awkward lifts and strain on your back. A rigid crotch pad stays upright while you settle them, and clever magnetic belt holders keep the buckle tongues tucked to the sides, so there’s no fishing around underneath your child for straps.

Sirona Si or Sirona S?

The Sirona Si is a complete, all-in-one seat with its own built-in ISOFIX base, so it’s ideal if you want a dedicated rear-facing seat for one car or a straightforward second-car setup. If you’d prefer a modular system, the CYBEX Sirona S Rotating Toddler Car Seat fits the CYBEX Base S 360° Rotating ISOFIX Car Seat Base, which also takes the CYBEX Cloud S Rotating Baby Car Seat and the CYBEX Anoris S Airbag Car Seat. Starting with a newborn? The CYBEX Cloud S Baby Car Seat with Base S Rotating Base is the complete starter system. The CYBEX Anoris Si Airbag Car Seat also has an integrated base, and when your child eventually outgrows their seat, the CYBEX Solution S High Back Booster Car Seat continues the S-Line journey up to 12 years. As the UK’s extended rear-facing specialists, we’ll always help you keep your child rear-facing for as long as possible with the best advice.

For extra peace of mind, the Sirona Si works with CYBEX SensorSafe, a child-in-car alert system that sends notifications to your smartphone. On Style variants, the XXL integrated sun canopy with UPF50+**** and a breathable mesh window keeps the sun off while letting air circulate, and clips off easily when you don’t need it.

Compare the Sirona Si with the rest of our baby car seats, infant carrier car seats, the wider CYBEX car seats line-up, or everything CYBEX at Little Peas. You can also browse our full car seats collection.

Want to see the S-Line in person? Visit our Dunfermline showroom to get a demonstration of the Sirona Si in your own car. To explore the full Platinum S-Line family, visit CYBEX.

*Compared with the same seat in a forward-facing position during a frontal impact, based on CYBEX internal testing.
**Compared with the same seat without L.S.P., based on CYBEX internal testing.
***Compared with the predecessor model.
****Except for mesh parts.

CYBEX Sirona Si Specifications

*Compared with the same seat in a forward-facing position during a frontal impact, based on CYBEX internal testing. **Compared with the same seat without L.S.P., based on CYBEX internal testing. ***Compared with the predecessor model.