This is the one. bye aero tube. - Spikes Tactical Melonited Gas Tube

This is an excellent gas tube with a quality finish that does not residue off and is more rigid than the Aero melonite gas tube. Spikes tactical is a decent company with a handful of exceptional items, this being one along with their crushed tungsten buffers, buffer system parts (steel castle nuts), lower part kits, and a couple others. Highly recommended