A high back booster provides the best protection after your child outgrows a convertible car seat. A child who has outgrown his convertible seat, yet weighs less than 40 lbs. If a child weighs more than 40 lbs., but the vehicle only has rear seat lap belts, contact an automobile dealer about installing shoulder belts in the rear seat. Most 40 lb. Many young children do not sit still enough or straight enough to keep lap belts low across their thighs.
Boosters are comfortable for children because they allow their legs to bend normally.
This also reduces slouching, one cause of poor lap belt fit.