Scotch-Brite(TM) Roloc(TM) High Strength Disc TR, 4 in x NH A VFN, 25 per inner 100 per case Durable, tough disc excellent for conformable deburring, satin finishing, and cleaning. A threaded attachment system secures the disc to the holder. Abrasive mineral: Very fine grade aluminum oxide. Color: Maroon MOS: 12000 RPM