The Britax Roundabout 55 Convertible Car Seat, Onyx features SafeCells designed to compress in a crash, significantly lowering the center of gravity and counteracting the forward rotation of the child seat which normally propels the child toward the front seat. It also has integrated steel bars to ensure that any accidents will not put your child in harm�s. The tether that come with most strollers and carriers feel like dog collars. This is the main reason why parents are encouraged to go with the Britax Roundabout 55 Convertible Car Seat, Onyx particularly if they have a toddler and they really need to travel. If you purchase the Britax Roundabout 55 Convertible Car Seat, Onyx, you will be able to ensure that your baby remains safe and comfortable.