Hoppe's Black Gun Grease is step four of five step in the Hoppe's Black High-Performance Gun Cleaning System. This gun grease formula reduces friction between moving parts, decrease wear and tear on firearms, and includes rust prohibitors to help protect your firearm against rust. It has a wide temperature range of -65F to 540F, so it will stand up to high round counts and will not gum up under extreme temperatures. Simply remove the grease cap and depress the plunger to apply Hoppe's Black Gun grease to clean, moving parts of the firearm.