Listing is for four (4) Service Caster Series #20 swivel casters, two (2) swivel & (2) swivel with top lock brakes, with a 3” diameter by 1-1/4” wide gray poly wheels and a 7/8″ square stem. Supports a total weight of 1,000lbs (250lbs/caster). When searching for a reliable and durable solution to your caster needs, consider Service Caster’s Series 20 square stem polyurethane casters.The Service Caster Series 20 is ideal for light and medium duty material handling, carts, equipment, and shop projects. The zinc plated finish provides durability under any condition, while the non-marking, non-marring polyurethane wheels perform especially well on hard surfaces such as concrete, tile, and wood. The square stems are designed to be bolted or riveted onto the inside of angled iron legs or against any flat surface. All rolling on a finely crafted ball bearing design that keeps you moving forward.