The Cybex Aton 2 Base is for use with the Cybex Aton 2 and Cybex Q Infant Car Seat. Additional base is perfect for multi-car families, allowing you to just conveniently attach infant car seat to the pre-installed base no matter which car you’ll be using with baby. The load leg prevents the seat from rotating forward in a crash and allows the seat to perfectly support the baby’s head, neck and body.