Silicon Polishing Bullet - 100 Grit (White) Premium silicon-carbide wheels formulated to provide the smoothest finish without the use of messy polishing compounds. This bullet is 1" x 1/4" and is grit 100 (coarse). Coarse pre-polish bullet for smoothing surfaces. Operating speed range is 5000 to 12,000 rpm. Supplied as a package of a dozen.