This 16" 5.56 NATO upper boasts an A2 profile, phosphate-finished barrel with a 1:7 twist, M4 extension, and carbine gas system. With a .750" low-profile gas block, 13.5" Lightweight Hex M-Lok Free Float Rail, and A2 flash hider. The hard coat anodized black, forged 7075-T6 A3 AR upper has M4 feedramp cuts. A shot-peened, Mil-spec Carpenter 158 steel bolt carrier group with staked gas key and charging handle is part of this assembly.