Description The JG M4 S-System is an exact replica of the famous assault rifle that is in use with the U.S. Military today. It comes with a retractable stock that makes this gun great for CQB and outdoor. The working charging handle gives this gun a realistic action that even higher priced guns like CA do not have. The S-System also has flip-up sights that fold down to give optics an unobstructed view. It also features an exclusive rail system that has a rail that bridges the traditional gap between the handguard and the receiver. JG AEGs are fully upgradeable and compatible with most after market external and internal parts. This airsoft gun includes a metal hi-capacity magazine and is also compatible with other major brands of standard and high capacity after market magazines. : S-System Style RIS : Retractable Stock : Flip-UP Front & Rear Sights : Functional Bolt & Charging Handle : high torque motor : precision metal gearbox : M120 grade spring : Integrated barrel for increased shooting accuracy and starting speed