Standard flat-top upper receiver with 10.5 chrome lined 1:7 twist 5.56 barrel.Comes with forward assist, port door, sling swivel, front sight post, and gas tube installed. Utilizes the mil-spec barrel nut and delta ring assembly to affix the barrel. Handguards, charging handle and BCG not included.Barrel Length:10.5 in / 266 mmBarrel Material:ChromeCaliber:5.56x45Color:BlackOperating Method:Direct ImpingementRifling Twist Rate:1:7"Selector:Safe/Semi