This plate caster has a zinc finish and a 1 1/2 x 5-inch cast iron wheel with a silver core. Each medium-duty caster features a double ball raceway swivel sub-type 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. Use item number WCS515B 5/8 for replacement wheels.