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.