Barrel: 11.5" 4150V Chrome Moly Vanadium steel, phosphate coated and chambered in 5.56 NATO with a 1 in 7" twist. The carbine-length gas barrel is finished off with a PSA 10.5" Lightweight Hex Full Picatinny M-Lok Free Float Rail, a low profile gas block, and an A2 flash hider. Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized black for durability. Featuring a mil-spec finish, these uppers are made for us right here in the USA by a mil-spec manufacturer. Bolt: The bolt is made of Mil-spec shot-peened Carpenter 158 steel. The gas key is secured with grade 8 fasteners and staked per mil-spec. Build Kit: A high-quality lower build kit with everything you need to assemble your AR-15 lower into a pistol. The pistol kit includes an SBA3 pistol stabilizing brace, Magpul MOE Pistol grip, Magpul MOE polymer trigger guard, PSA Enhanced Polished Trigger Group (EPT), carbine buffer spring, and standard carbine buffer.