Spikes Tactical SUGT0M4 Gas Tube for AR-15 Rifle Length. The SUGT0M4 is designed for the AR-15 gas system. Gas tube is Mil-Spec 304 stainless steel with a Melonite coating for improved heat resistance, corrosion resistance, and reduced reflection. Suitable for .223/5.56 uppers and also compatible with 5.45 uppers. Included is a split roll pin.