Britax What makes the Britax Companion Infant Car Seat different from other infant car seats? The same thing that makes Britax Convertible Car Seats the best – a renowned focus on safety and comfort. The Companion features a true side impact protection head pad with adjustable air filled pockets that expand for a customized fit. Car seat includes an anti-rebound bar on the base which reduces rebound movement on impact. The Britax premium comfort pads protect your baby’s delicate skin from coming in contact with the harness, so your little one can relax in comfort. Car seat can be removed from the base to become a carrier or you can attach it to the Britax Preview Stroller for a comfortable travel system.