Our heavy duty adjustable glide is designed for office furniture and other heavy items. The durable, non-marking base stands while the cover turns the screw in a low-friction mechanism with or without ball bearing system. The base is 9/16" high x 2" diameter with a 5/16" screw and an adjustable range of 1⅜". The base is also made of black polypropylene while the stem is zinc-plated steel. Sold by the each, max load: 400 lbs. per set of 4 Corrosion resistant and adjustable under full weight!