Majorly, you use die grinder stone bits for cutting, deburring, polishing, and cleaning stone. But also you use them on alloy steel, wood, carbon steel, stainless steel, etc. When you mount on 6mm (1/4") shank, apply 20,000 RPM. While mounting on 3mm (1/8") shank, there is going to be a higher speed. You can find Syndent die grinder stone ...