Convertible car seats, which hold infants in the rear-facing position and toddlers in the forward-facing position, offer parents the longest useable time for their money. Most newborns are big enough to ride safely in a convertible car seat, and since most of these car seats have a 40 pound upper limit, toddlers can generally use a convertible seat forward-facing through their second or third birthday. If you're shopping for a convertible car seat, here are the top six convertible car seats, each offering safety and convenience for new parents, chosen by your Baby Products Guide.