Material: SteelPacking: 30PCS/ Set1. 30pcs of Diamond Electroplated Tools suitable for electrical grinding machine， engraving machine， etc2. Used for metal， wood， glass， jewelry， ceramic， stone material and others3. Ideal correcting tool for model processing 30Pcs Diamond Coated Burr Rotary Grinding Head Polishing Nail Surface Grinding Tools (Nail Electric Machine Grinding Accessories)