This caster features a swivel sub-type and a wheel brake. Each caster has a silver-core rubber wheel measuring 1 1/2 x 5 inches and a load rating of 500 pounds. The mounting plate measures 4 1/8 x 3 3/8 inches, with a 5/16-inch mounting bolt diameter and an inside/outside bolt hole spacing of 2 3/8 x 3 1/8 inches. The frame is made from steel with a zinc finish. Use the item number WRT515B for replacement wheels.