This synthetic lube is a perfluoropolyether, one of the most inert materials known. The brand is Christolube MCG 111, NOT to be confused with Dow 111 silicone grease which is NOT O2 compatible. Unlike other synthetic O2 lubes, this one does NOT get viscous at low temperatures and works well in regulators used in cold waters. Use this grease in regulators or diving gear exposed to gas mixtures containing O2 levels of 23% or more. For Nitrox and O2 applications, Oxy-compatible lubricants must be used inside regulators or valves. One of the best fluorocarbon greases is Christolube which is fully compatible with pure O2 and retains high lubricity even in ice water environments. Navy approved, 2 oz. Tube.