ARES M4 Slim Pistol Grip + High Torque Slim AEG Motor
suitable for the M4 series AEGs.
Made of steel and will make sure your AEG efficiently.
Do make sure the gears in your AEG are compatible with high torque motors. 
All aftermarket upgrade parts require necessary skill or modification to install and assemble, please consult with your airsoft technician if needed