4" x 2" Mold-On Rubber Cast Swivel Caster w/ Total Lock Brake - 400 lbs. Cap.4" x 2" Mold On Rubber Cast Wheel Swivel Caster with Total Lock Brake The mold on rubber cast wheel is an economic wheel, providing a cushion while rolling on a strong cast iron core. This wheel performs best in dry applications. Tread: Rubber Vulcanized To Core Core: Cast Iron Bearing: Roller Bearing Rig: Zinc Plated Swivel Caster, 4" x 4 1 2" Mounting Plate, Total Lock Brake Capacity: 400 Lbs. Color: Black Durometer: Shore A 80 (+ 5) Temperature