The X-Series is our top selling solid plastic stacking chair, available in four sizes. Our 18 1/2'' A+ chair has an oversized seat and back designed for today's larger and taller students. MODEL SHAPE HEIGHT X108 A+ 18.5'' X107 A 18'' X105 B 15.5'' X103 C 13.5'' X101 D 11.5''OPTIONSNon-Skid GlidesQ-Ball GlidesSteel Glides