APS Quick Change Spring System Ambidextrous Silver Edge Extreme 8mm German Bearing V2 Version 2 Gearbox For M4 M16 Series AEG EBB Rifles Airsoft Rear WiredAPS Ambidextrous Silver Edge Extreme 8mm German Bearing V2 Gearbox Rear Wire Ambidextrous V2 Gear Box. 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 the