Black Emery for copper, brass, aluminum, steel, stainless steel, nickel, and iron. Aluminum Oxide based compound is used for "cutting" the surface to remove scratches prior to fine polishing. Features: Applied on buffing wheels. Excellent "cutting compound" for removing scratches and making surface smooth. Use on metals such as copper, brass, aluminum, steel, stainless steel, nickel, and iron NOT recommended for buffing plastics and softer metals such as gold and silver. Tallow grease base (with high melting point) impregnated with aluminum oxide4-oz Bar measures approximately 1in. x 1in. x 5in.Packaged in retail packaging.