The G&G Pinion Gear is the OEM Replacement part for G&G Airsoft AEG rifles but will work in most Version 2, Version 3 and Version 6 airsoft metal gearboxes. The Pinion Gear is attached to the motor and connects the motor to the gearbox. A Stripped or worn pinion gear can cause gearbox lockups, grinding and stripping of other gears. Keep your AEG running at its best by replacing worn and damaged parts!