White Aluminium Oxide grinding wheels are a preferred choice for general tool sharpening of high carbon and HSS tools. Compared to general purpose grey grinding wheels, white wheels cut much cooler with far less tendency to overheat a tool's edge (if you press hard enough for long enough you can still blue the edge). These 120 Grit white grinding wheels have a medium hard vitrified bond with a medium structure. They are friable and cut freely offering a fast result and clean finish. The wheels have a 31.75mm bore (bore reduction bushes are available).