GMC 1998 Savana Van Owner's Manual page 57

A booster seat (F, G) is designed for children who
are about 40 to 60 lbs. (18 to 27 kg) and about
four to eight years of age. It's designed to improve
the fit of the vehicle's safety belt system. Booster
seats with shields use lap-only belts; however,
booster seats without shields use lap-shoulder
belts. Booster seats can also help a child to see
out the window.
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