5.56 NATO cal., ALG QMS fire control group, 16 in. machine gun steel micro-pinned barrel, A2 flash hider, ambi mag. catch, Magpul SL stock and grip, reversible bar stock steel selector, enhanced forged upper and lower receiver, ambi bolt release, HDSI wedge lock M-LOK handguard, Gen III ambi charging handle, H or H2 buffer, 6-position Mil-Spec receiver extension, enhanced pivot and takedown pins, bar stock forward assist, Type III hardcoat anodized black finish.