Classic design since 1962. Millions of units in the field supporting children of all ages. MODEL SHAPE HEIGHT 7108 - Stack Chair A+ 18.5'' 7107 - Stack Chair A 17.5'' 7105 - Stack Chair B 15.5'' 7103 - Stack Chair C 13.5'' 7101 - Stack Chair D 11.5'' 710P - Music Chair A+ 18.5'' 7109 - Music Chair A 17.5'' 7148 - With Ganging Device A+ 18.5'' 7147 - With Ganging Device A 17.5'' 7158 - With Bookrack A+ 18.5'' 7157 - With Bookrack A 17.5'' 7155 - With Bookrack B 15.5''OPTIONSSeat and Back Pads (A+ and A sizes only)Non-Skid GlideQ-Ball GlideSteel GlidesArm Package (7108 and 7107 only)