Use this swivel caster for most medium-duty jobs, carrying objects as heavy as 400 pounds. This caster has a four-inch cast iron wheel with a 1 1/2-inch wide rubber tread and a zinc-coated steel frame with a brake system. The mounting plate is 4 1/8 inches long and 3 3/8 inches wide with a bolt diameter of 5/16 inches. The bolt spacing measures 2 3/8 inches long and 3 1/8 inches wide.