This is a set of optional ST Racing Concepts CNC Machined Aluminum Hex Adapters, and are intended for use with the Traxxas Slash 4x4. These 12mm Hex adapters securely mount on your Slash 4x4 tires and wheels with no chance of the adapters being rounded off under heavy torque and power loads. Set screws on the hex adapters securely hold them in place on the stock axles (May not be compatible with aftermarket axles). These parts are CNC machined from high quality aluminum and anodized red, for durability and good looks.