TRAXXAS Gear adapter, fixed, Rustler 4X4 VXL 38-6790 Description: Fixed gear adapters take the guesswork out of setting your gear mesh with five preset gearing positions. Place the adapter in the aluminum motor plate and insert the motor screw through the desired position for a perfect gear mesh every time. Fixed Gear Adapters also keep the motor from shifting under hard impacts or big-air landings. Replacement part for these models: Rustler 4X4 VXL Rustler 4X4