... Environmentally friendly long durability Certificate:ISO Steel Shot Peening:Normal:40-50HRC (377-509HV)Special:52-56HRC ( ... 543-620HV)Special:56-60HRC (620-713HV)Steel Shot PeeningSize: S930,S780 S660 S550 S460 S390 S330 S280 ... used for sand and rusts removing of cast iron ,cast steel, steel structures, steel plate, steel pipes, forging and surface treatment of oxidized workpieces.