RA-TECH Magnetic Locking NPAS Adjustable Loading Nozzle System for VFC M4 / HK416 GBBR Series. Brand new imported from Taiwan! Velocity adjustable design, to adapt to weather and temperature condition. With steel nozzle head. Better freezing resistance. Saving gas consumption. More consistent muzzle velocity. More smooth bbs feeding. Muzzle velocity adjustable. Patented RA-TECH magnetic locking system.