7/8" Silicon Polishing Wheel (Knife Edge) - 100 Grit, pkg of 12 Premium silicon-carbide wheels formulated to provide the smoothest finish without the use of messy polishing compounds. Edge is square and grit is coarse (grit 100). Coarse pre-polish wheels for smoothing surfaces. Operating speed range is 5000 to 12,000 rpm. Supplied as a package of a dozen.