This is an optional Traxxas Single Motor Gear Cover, and is intended for use with the E-Revo model 5605. Traxxas makes it easy to convert from dual motors to a single brushless motor setup with a clean factory fit and finish. Choose your favorite electric power plant and bolt it in using the Traxxas single motor gear cover and blue-anodized aluminum motor plate (TRA5690X). The one-piece gear cover keeps dirt and debris out, while allowing easy access to the pinion and spur gear. Slipper clutch adjustments are easy thanks to the exposed slipper nut.