Fly backwards or decelerate during a dive. EVP unit makes 3D planes 4D planes. Includes necessary parts for assembling a 9-3/4" diameter electric variable and reverse pitch propeller. Adapts to airplanes capable of flying with our AXI 2208/34 motor. The unit is designed for use with Model Motors EVP0834 Hollow Shaft AXI 2208/34 Outrunner motor and either a Jeti 12 amp controller or the Jeti 15 amp Helicopter controller with governor mode. Detailed instructions for assembly and set up included.