This wheel is a genuine OEM replacement part used in portable air compressors. It consists of a plastic rim and rubber tire with an outer diameter of 9.5 inches. It is held in place on the compressor axle by a shoulder bolt and nut. The wheel allows the equipment to move smoothly during use. If the tire is punctured, or the rim is damaged, the wheel will need to be replaced to restore the portability of your equipment. If the nut and bolt are worn down, it is recommended to replace them at the same time. Remove the nut and bolt that secure the wheel and pull it off the axle. Place the new wheel in position and secure it with the fasteners (sold separately). Each wheel is sold individually.