5/8" Silicon Polishing Wheel (Knife Edge) - 1200 Grit, pkg of 12 Premium silicon-carbide wheels formulated to provide the smoothest finish without the use of messy polishing compounds. This wheel comes in 2 sizes; 5/8" and 7/8". Edge is knife. Ultra fine, soft and flexible for a super high lustre; final finish, medium lustre or smooth matte finish. Operating speed range is 5000 to 10,000 rpm.