Heavy-duty, high density linear polyethylene shells are 40% heavier then many similar chairs. Non-exposed rivets secure the frame to the shell's integral underside ribs. Balanced to set upside down on desks or tables 16-gauge tubular steel legs. Self-leveling glides. Stackable up to 20 chairs 12 seat colors available. Nylon base glides. Made in the USA. 10 year manufacturers warranty. Available in XL size! 18 1/2" seat height.