CASTERS YOU CAN KEEP FOR LIFE - Our Premium substitute caster wheel stem diameter is 7/16 inch(11mm),stem size is 7/8 inch(22mm),The heavy duty design helps up to 500 lbs as a group of 5SMOOTH & QUIET ROLLING - Wheel materials are manufactured from high quality polyurethanes, that are high mechanical strength, wear resistance, shock absorption and low-noise. These points assist roll smoothly and trigger no squeaky sounds or noise of any kind.SAFE FOR FLOORS - Smoothly and quietly roll around on any hardwood, ceramic tile, wood, carpet, particularly cement floors with out scratching, please pay attention to security due to less resistance forceEASY TO INSTALL - Simply pull your previous casters out, then plug the hot wheels in, universally match for different regular seats: paintings stools, workplace chairs, dining chairs, table wheels, device carts etccolour:BlackMaterial:PUsize:50mmPackage Contents:5 x Caster WheelsOnly the above package content, different merchandise are usually not included.Note: Light shooting and diverse displays could cause the colour of the article within the photo a bit assorted from the genuine thing. The dimension allowed error is +/- 1-3cm.