Dremel 412 - 36pc Medium/220 Grit Aluminum Oxide Sanding Discs. Tube Packaged. Use with 1/16 inch Screw Mandrel which is not included. For use with Dremel Rotary Tools. The recommended RPMs for aluminum, brass, copper and platic are 10 - 15,000. For hard or soft woods 30,000 RPMs is recommended.