Listing is for a set of four (4) service caster series #30 casters, two (2) swivel casters with bolt on swivel locks and two (2) swivel casters with side lock brakes, with 8" diameter by 2" wide polyurethane tread set on a polyolefin core wheel and maintenance free precision ball wheel bearings capable of supporting a total weight of 4,000 lbs. (1,000 lbs./caster).