Spike's tactical has produced what they believe is the best gas tube out on the market for the ar-15 rifle.The gas tubes are made out of mil-spec 304 stainless steel and then are melonite coated for greater heat resistance, corrosion resistance, and lower reflection.These gas tubes are not only great for.223/5.56 uppers but are perfect for 5.45 uppers for when you shoot cheap surplus corrosive ammunition.These are the same gas tubes that are installed on their st-15 rifles and all of their complete upper receivers.The gas tubes also come with a split roll pin.Finish: Black MeloniteType: Gas BlockModel: Gas TubeSize: Carbine LengthMaterial: 304 Stainless Steel