This is a fully machined upper and 80% machined lower receiver. No FFL required. Parts are machined to spec so that all accessories will fit. These is made from a foraged 7075 T6 Aluminum and the magwell is broached for a perfect fit. This set is bead blasted and powder coated black. Upper gas tube hole is round that will accommodate a piston gas system. Can also be used with traditional gas system. Upper also has forward assist.