FLITZ PRECLEAN IS AN INDUSTRIAL STRENGTH FORMULA FOR REMOVING HEAVILY ENCRUSTED CORROSION , RUST, LIME, TARNISH, GREASE, OIL, AND WATER STAINS. UNMATCHED FOR ITS PERFORMANCE ON ALUMINUM. (CAN BE USED PRIOR TO THE BUFFING PROCESS.)  SAFE FOR PAINTED AND FIBERGLASS SURFACES TOO. NOT INTENDED FOR USE ON CHROME. (AVAILABLE IN GALLON SIZE IN A CASE OF 4; ALSO 5 GALLON PAIL; SEE UNDER SPECIALTY PRODUCTS, "BY THE CASE.")