All YHM dust cover assemblies are made from steel and plated with a corrosion and dent resistant black finish per mil-spec. They mount easily using an AR-15 pattern bolt and includes the upper and lower receivers. Bolt carrier group and forward assist are not included.Machined from steel and plated with a corrosion and dent resistant black finish.The gas key, dust cover, and barrel nut do not come with any other parts or hardware.Machined from steelForward and upper receivers are not included.Ford upper receivers based on a AR-15 pattern barrel.Called 6.8 SPC.