APS Silver Edge Extreme 8mm German Bearing QD Version 2 V2 Gearbox For M4 M16 Series AEG Rifles AirsoftAPS Silver Edge Extreme 8mm German Bearing QD Version 2 V2 Gearbox For M4 M16 Series AEG Rifles Airsoft Quick Change Spring System Polished and Buffed surface improves smoothness. 8mm Bearing Bushings, Bearing Piston Head and Bearing Spring Guide used. Comes with Blow Back Plate. Prevent Corrosion. The Quick Change Spring Guide has 4 locking legs instead of 2 which is different from the existing spring guide found in the market which further secure