Tamiya Hop-Up Options 53569 6mm Thick Clam Type Aluminum Wheel HubThese machined aluminum hubs clamp to the wheel axle rather than the slip on plastic units found on many of Tamiya's kits. The use of aluminum wheel axles results in a truer spinning wheel and added strength. Furthermore, the drive pin stays secure as the whole assembly is fastened with hex screw. Set includes four hubs and hardware.