Our 100 grit provides a finer edge. The very fine 150 grit is the finest grinding wheel we carry. After grinding, a few strokes on a bench stone and your tools are ready for use. This wheel is a J Grade. The 8" wheel has a 1" arbor hole with bushings for 7/8", 3/4" and 5/8" arbors and is rated for 3600 rpm.