This rigid plate caster features a 1 1/2 x 5-inch phenolic wheel with a black core. Each medium-duty caster has a double ball raceway swivel sub-type and a load rating of 350 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 zinc with a zinc finish. Use item number 5-5-339 for replacement wheels.