These are 4mm wheel hubs used in many of Tamiya’s RC on-road cars. They replace the standard plastic hub found in stock kits. A slit is provided in the wheel hub, and the gap is tightened with a cap screw. This method of attachment more securely fixes the wheel axle to the hub thereby avoiding accidentally dropping the 2 x 10 mm stainless steel shaft when removing the wheel. Furthermore, because it is made of aluminum, you get more accuracy, rigidity, and precision when mounting wheels to your car.
