This car seat bundle pairs the Britax One4Life all-in-one convertible car seat with the Britax Poplar S slim convertible car seat to cover your child's needs from birth through the booster seat years. The One4Life converts from a rear-facing infant seat to a forward-facing harness seat and finally a high-back booster, accommodating children 5-120 lbs and up to 63 inches tall. Its click-tight installation system, no-rethread harness with 15 positions, and 9 recline angles make adjusting the seat easy as your child grows. Safety features include a steel frame, SafeCell crumple zone, and side-impact protection. The Poplar S starts as a rear-facing seat for infants up to 50 lbs then converts to forward-facing. Its slim 17-inch design allows for a 3-across fit in most vehicles, with patented Britax safety features like a steel frame, SafeCell technology, and V-shaped top tether. The click-tight system, 14-position harness, and multiple recline angles also make installation and adjustments simple. With stages from birth through elementary school, this bundle provides a seamless transition that combines the One4Life's full lifespan coverage with the Poplar S's space-saving design - giving you adaptable, trusted protection in one purchase.