The Baby Jogger Car Seat Adaptor is one of the most important accessories you will ever purchase for your stroller. It allows you to use your car seat with your stroller until your baby is strong enough to be placed in a stroller seat. It is designed to fit several popular car seats including, Peg Perego Primo Viaggio, Britax Companion, Maxi Cosi and most Graco and Evenflo car seat models.