With the onSide air™ Convertible Car Seat by Safety 1st, you can keep your child rear-facing all the way up to 40 pounds! The car seat features our advanced Air Protect®technology for better protection around the head, where it's needed most. The Air Protect system works to protect your child in two vital ways. In a side impact collision, Air Protect® immediately safeguards your child by diminishing the forces of the crash. In a second layer of defense, the system allows air to escape from the headrest: channeling more crash energy away from your child. It is this double layer of protection that makes Air Protect® technology unique. Other features include 4 harness heights and 3 buckle positions that make the seat adjustable and secure, a removable cup holder and a hand washable seat pad. The onSide air™ Convertible Car Seat is also airplane ready.