The AR-15 Complete Upper Assembly comes everything you need. It has a 16″ Parkerized barrel with a 1:7 twist rate. It also comes with a 15” lightweight Key Mod rail and upper receiver along with the bolt carrier group and charging handle. The upper is chambered in 5.56 NATO and the receiver and barrel extension are machined to include M4 feed ramps. This upper assembly also includes an A2 flash hider.