This medium-duty swivel caster features a 1 1/2 x 5-inch black urethane wheel and a load rating of 450 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 item number MPU515B 5/8 for replacement wheels.