Bench Grinder Stones Wheels. Available in 6", 8" and 10" diameters. 6" stone available in 3/4" or 1" thickness. Comes in 24 Grit, 36 Grit, 46 Grit, 60 Grit, and 80 Grit. High quality aluminum oxide and gray in color. 6" grinding stone: 4456 max rpm. 8" grinding stone: 3600 max rpm. 10" grinding stone: 2483 max rpm.