This 6" x 2-1/2" Solid Elastomer Rigid Caster consists of pressed steel, ball protection by the special top plate and ball disc design. Features: Bolted wheel axle and Zinc-plated. This caster includes rich-quality reaction-injected polyurethane-elastomer, very high operational comfort through the especially thick, elastic tread, low-noise operation, low rolling resistance, excellent floor conservation, very high chafting resistance, high cut and tear propagation resistance, and very good chemical linkage with the wheel center.