Sled based frame for use on carpeted surfaces. MODEL SHAPE HEIGHT D00X A+ 18'' D00A A 18'' D00B B 16'' D00C C 14'' D05X - BRK A+ 18'' D05A - BRK A 18''OPTIONSWire Bookrack (A+ and A sizes only)Seat and Back PadsSeat Pad OnlyNylon Glides