The DBOYS M4 S.I.R. RIS Full Metal Airsoft AEG Rifle brings strong competition to the CASV variant M4 style rifle market. With a large front RIS rail system that continues from the upper receiver to the front sight making it rock solid even when supporting many accessories such as lights, lasers, grips, launchers, and optics. The rail also easily opens to store the included 8.4v NiMH brick style battery. With a Version 2 Gearbox with M120 spring, this rifle fires 390-400 FS with 0.20g BBs upwards of 150 feet. Flip up adjustable front and rear sights can be used alone or with aftermarket optics such as red dots or scopes. Also included with this rifle are a basic charger, polymer vertical foregrip, and metal 300 BB high capacity magazine. This full metal rifle is both durable and reliable for skirmishing both indoors and on the field.