3-1/4" x 2" Polyon Cast Wheel Swivel Caster - 500 lbs. Capacity3 1 4" x 2" Polyon Cast Wheel Swivel Caster Polyurethane elastomer tread chemically bonded to a cast iron core. These wheels are somewhat heavy and are ideal for warehouses with concrete and hardwood flooring. Tread: Polyurethane Elastomer Core: Cast Iron Bearing: Roller Bearing Rig: Zinc Plated Swivel Caster, 4" x 4 1 2" Mounting Plate Capacity: 500 Lbs. Color: Green and Black Durometer: Shore A 95 (+ 5) Temperature Range: 40 F to 180 F Load Capacity