Daniel Defense M4A1, Semi-automatic Rifle, AR, 223 Remington/556 NATO, 14.5 Hammer Forged Barrel (16 OAL with Pinned Brake), Daniel Defense Flash Hider, Anodized Finish, Black, Carbine Length Gas System, Flat Dark Earth M4A1 Rail Interface System (RIS) II, Daniel Defense Furniture, 32 Rounds, 1 Magazine 02-088-06027-011 The M4A1 AR15 style firearm features the RIS II picatinny quad rail, which has been in use by US Special Operations Command (SOCOM) for the SOPMOD Block II program since 2005. The M4A1 is built around a 14.5 inch Cold Hammer Forged M4 Profile barrel with a permanently attached Daniel Defense Flash Suppressor. The independently ambi GRIP-N-RIP Charging Handle accommodates left- and right-handed shooters.