jg airsoft m 4 s-system full metal gearbox black aeg rifle w/ integrated ris and high performance tight bore barrel - newest enhanced model(Airsoft Gun) Metal Gearbox, Functional Safety Switch, Realistic Weight Retractable Stock Semi and Fully Automatic, Adjustable Hop-Up System Adjustable Metal Front and Rear Sights, Spring Grade 110 Metal RIS, (Railing System) Metal Outer Barrel, Metal Magazine Motor Type: Stock Long Type Motor Made by JG, Version 2 Gearbox