CuBUSTER is chemically formulated to act on heavy layers of copper and to treat heavy copper fouling in rifles and sidearms. This product is especially for guns that are not regularly cleaned and require intensive cleaning care. A blue indicator on your cleaning patch will confirm an effective copper removal from the barrel. You will go bananas for CuBUSTER's extremely effective copper removal together with its light tropical scent.CuBUSTER is the ultimate copper stalker to restore your heavily fouled firearm to its former glory."BRING FORTH THE MARKSMAN in you"