Natural Lube 1000 Plus Bore Butter by Thompson Center Arms is a biodegradable all-natural lubricant that does not contain petroleum-based oil or additives. This lubricant reacts chemically different to the combustion of black powder, producing far less tar-like fouling. The 5 oz tube is ideally suited for easy application on patches, and this lubricant can also be used to lube bullets. The Natural Lube 1000 Plus Bore Butter is an excellent rust preventative on the external surfaces of any firearm.