SHS One Piece Bore Up Cylinder Piston Head Air Nozzle Set For M4 M16 Series AEG Gearbox Rifles AirsoftSHS One Piece Bore Up Cylinder Piston Head Air Nozzle Set For M4 M16 Series AEG Gearbox Rifles Airsoft Made out of steel & plastic With Thread cylinder set for AEG rifle gearbox Version 2. Included Air Nozzle and Bearing Piston Head. Cylinder head set for Version 2 series gearbox. Silent piston head with ball bearing. Tighter sealed air nozzle ensures more barrel exit muzzle velocity. Higher power, better performance. 363mm~500mm precision inner