The zirconia grain is supported by grinding additives which lubricate and cool the area being ground and help prevent clogging, prolonging the effective life of the disc. Max. speed (rpm): 13,300 Diameter: 115mm Bore diameter: 22mm Vacuum design: plain Abrasive material: Zirconium For use on all types of stainless steels, weld seams, castings and other sophisticated metals for extended periods