Regulator O-rings that are used with enriched air gas mixtures are required to be lubricated with lubricants that meet specific requirements. Using the proper lubricant when diving Nitrox is not only important, but can be life saving. Enriched air nitrox use requires a lubrication that is non-carbon based. ChristoLube "129" meets that requirement. This 1/4 oz screw-cap container is a must for any Nitrox divers Save-A-Dive Kit.