HPI Racing cast metal Hex Wheel Hubs are now available for the RS4 MT line of nitro and electric trucks from HPI Racing. These metal parts replace the stock plastic hubs for a strong and secure wheel mounting system. The cast metal design resists deformation, allowing the wheel nut to be clamped down more firmly than when using plastic hubs. Built-in ribs help grab the wheel for added security. Originally designed to help cope with the extreme power of the 18SS engine in the Nitro RS4 MT 2 18SS kit, these metal hubs are a low cost upgrade to the Nitro MT, Nitro MT 2, electric MT, and can be used on the rear wheels of the Nitro Rush trucks.