Porter Cable's metal cleaning and polishing compounds are available in a range of five different grades for everything from aggressive heavy-duty cleaning (#1) to fine high-gloss polishing (#5). This is the #4 compound, the first of the polishing compounds used after cleaning. Its gentle cut is perfectly suited for light buffing and polishing on all metals, and is ideal for brass hardware, tools and knives. It is intended for use with a powered buffing wheel. Simply turn on your buffer, coat the wheel with compound, and you're ready to go.