KING DO WAY 5 Pcs Diamond Wheel Set With 50mm Emery Coated Cutting Diamond Discs Drill Bit + 1 Pcs Mandrel Fit Rotary Tool These high speed diamond coated cutting discs can be used with your rotary tool to cut a wide variety of materials. Cut wood, glass, plastic, metal, marble, masonry, stone, concrete,and fiberglass. For use in tight places and for flush cutting. Max Speed: 20,000 RPM Please add water for coolant when using diamond tools.