Rusteprufe Refill bottles are intended to be used to refill your Rusteprufe Applicator jar when your chamois starts to dry out. Simply pour the desired amount in the jar and let the chamois sit for a couple days. If it is still dry add some more Rusteprufe to your jar until your chamois is perfectly moist. Rusteprufe should be used on all metal parts of your weapon. Wet a patch and run it down your barrel to significantly reduce fouling and oil the barrel in one application.