This 8" x 2" Thermoplastic Round Gray Tread on Kingpinless Swivel Caster consists of pressed steel, with ball bearings in the swivel head, ball protection by the special top plate and ball disc design. Features: Bolted wheel axle and Zinc-plated. This caster includes rich-quality thermoplastic polyurethane, low-noise operation, low rolling and swivelling resistance, proper floor conservation, and very high chafing resistance. In addition it is chemically bonded for an indivisible linkage to the wheel center.