I bought this seat for my x-girlfriends kid and then we split up.  Her rear wasn't in this seat more than 5 times.

With new cool and sporty features, any child is sure to feel great riding around in the backless TurboBooster¨ youth booster seat. This backless version has padded, height-adjustable armrests and hide-away cup holders on either side of the seat - perfect for storing drinks, snacks, and toys for those long rides. The backless TurboBooster¨ youth booster seat is for children from 4 to 10 years old, from 40 lbs to 100 lbs and between 40 and 57 inches tall.