The One4Life Slim all-in-one car seat takes your child from birth to big kid with trusted Britax safety, ClickTight installation, and a slim SpaceSaver design. As a convertible and harness-2-booster seat in one, it grows with your child for 10 years. It starts rear-facing with an extended capacity of up to 35 lbs., so your child can ride rear-facing longer. It easily converts to forward-facing toddler mode (up to 65 lbs.) and high-back belt-positioning booster mode (up to 120 lbs.) when your child is ready. With a slim outside and spacious inside, the 17.5 seat is designed to fit 3 across* without compromising safety and comfort. ClickTight helps you install with confidence, every time. The base and shell are easy to wipe down for hassle-free cleanup. The car seat cover is safe to machine wash and dry, and its naturally flame-retardant with no added FR chemicals. One4Life Slim features a high-strength steel frame, a SafeCell crumple zone, and a V-shaped tether. As your child grows, you can easily adjust the 15-position no-rethread harness and headrest with one hand. With cooling channels, premium padding, three infant inserts, and built-in armrests, your child will love every ride. *Britax cannot guarantee 3-across fitment in all vehicles.