Only one in five young children ride in injury-reducing booster seats. That's according to a study from the National Highway Traffic Safety Administration, recommends the seats for kids ages four to eight who are under four feet nine inches tall. They fit children better than seat belts. The agency head says children are at unnecessary risk of being injured in crashes because they are either in the wrong restraint for their size, or worse, totally unrestrained. About a fifth of parents questioned said they believed booster seats were unstable and wouldn't protect the child. Not a problem, says the government, as long as the boosters are properly attached to the back seat. Parents also said they didn't use the booster seats because their trips were short or their child didn't like the seat.