CASTERS YOU CAN KEEP FOR - Premium replacement wheel stem diameter is 7/16 inch (11 mm), stem length is 7/8 inch (22 mm), heavy duty supports up to 500 lbs per set of 5 SMOOTH AND QUIET ROLLING - The wheel materials are made of high-quality polyurethanes, which have high mechanical strength, wear resistance, shock absorption and low noise. Features help to roll easily and cause no squeaking or noise. SAFE FOR - Roll smoothly and quietly on any hardwood, ceramic tile, wood, carpet, especially cement floors without scratching, please pay attention to safety due to the less resistance force EASY TO INSTALL - Simply pull out your old casters, then plug in the new wheels, universally suitable for various standard seating: work stools, office chairs, dining chairs, desk wheels, tool carts, etc. color: black Material: PU size: 50mm Package Contents: 5 x Casters Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of