Colt's commitment to quality and excellence are evident in every piece that leaves the factory. This complete upper assembly is no exception to that rule. Built from the factory as a complete upper assembly kit, not stripped from a rifle outside of the factory, you can rest assured you are purchasing a genuine Colt product. The upper features a 16" barrel with a 1:7" twist rate, a gorgeous monolithic free float quad rail and flip front sight base. The included bolt carrier group is full auto capable when using a select fire lower receiver, but will work just fine in semi auto lowers as well.