Cybex Sirona Si

Pre-order update: The Sirona Si comes ready to use with its Base S, and Cybex expects the first deliveries in December 2026, starting with Amber Brown in mid-December and the other colours by late December. Pre-order now to secure your seat from the first allocation rather than waiting for later shipments. Dates are Cybex's latest estimates and may change, and we'll keep you updated until your seat is on its way.

The CYBEX Sirona Si is a 360° rotating i-Size toddler car seat from the new CYBEX S-Line with an integrated ISOFIX base, so it's ready to use straight from the box. Rear-facing travel gives up to 50% better protection than forward-facing, and the one-hand 360° rotation makes side entry simple. Made to grow with your child to around 4.5 years.

Why parents choose the Sirona Si

• Up to 50% better protection rear-facing – a padded energy-absorbing shell distributes impact forces and holds your child close, with rear-facing travel to approx. 4.5 years.
• Comes with the Base S – a ready-to-use setup straight from the box, with smooth one-hand 180° rotation for easy side entry.
• Grows up to 4.5 years – CYBEX GrowTech adapts with your child (40–105 cm with the newborn inlay accessory), AGR-certified with an adjustable headrest, M-position and 40% more recline range.
• Use from 3 months to 4.5 years – removable inlays tailor the fit as your child grows; the Comfort inlay (included) supports them to 85 cm.
• One-hand 360° rotation – turn the seat to the door and lift your child in or out without straining your back.
• Magnetic belt holders – keep the belts tucked neatly aside for a calm, effortless loading experience.
• 25% more side-impact protection – the Linear Side-Impact Protection (L.S.P.) system channels energy into the energy-absorbing shell and headrest.
• Optimal breathability – 3D mesh fabric boosts airflow up to 6× versus conventional materials; SensorSafe is available for added reassurance.

Approved to UN R129/04. Suitable from approx. 3 months to 4.5 years (61–105 cm, max. 20 kg; from birth with the newborn inlay accessory). Supplied with the Base S.