|| SPECIFICATIONS || MATERIAL: STEEL, ALUMINUM, POLYCARBONATE, RUBBER COMPATIBILITY: M16-A2 FEATURES: - GROOVED STEEL CYLINDERS FOR HEAT DISSIPATION - STEEL BALLBEARING PISTON HEAD FOR SMOOTHER ROTATION OF SPRING DURING COMPRESSION - VENTILATION HOLES IN PISTON HEAD GREATLY INCREASES SPEED THAT THE PISTON TRAVELS FOR FASTER CYCLING - SIZE-MATCHED PISTON HEAD - CNC PROCESSED POLYCARBONATE AIR NOZZLE (W/ O-RING) FOR BETTER AIR SEAL