Scotch-Brite(TM) Hookit(TM) Clean and Finish Disc, 8 in x NH S ULF, 20 per case Used on rotating power tools, effective for light to moderate cleaning, satin finishing, scratch blending and deburring. Hookit(TM) backing reinforces disc for longer life. Silicon carbide mineral ultra fine grade. Color: grey MOS: 6,000 RPM