Description: Designed with metal shank, diamond head, high degree wear-resisting, highly active anti-clogging and good degree of finish. Perfect for sculpturing, dressing, precision grinding and internal grinding carbide in ceramic, glass, precious stone, alloy and many ther abrasive materials. Great to use with high speed rotary tools, grinders and drills. Necessary tool for DIY enthusiast or hobbyist or craft fan. Durable and reusable, save time and working procedure, easy to use. Specification: Material: Metal+Diamond Shank Diameter: 6mm/ 0.236 inch Size(Approx.): Head Diameter: 8mm(0.315 inch), 10mm(0.393 inch), 12mm(0.472 inch), 15mm(0.59 inch), 18mm(0.7 inch), 20mm(0.78 inch). Ball Length: 10mm(0.393 inch), 10mm(0.393 inch), 15mm(0.59 inch), 20mm(0.78 inch), 18mm(0.7 inch), 20mm(0.78 inch). Total Length: 50mm/ 1.97inch, 50mm/ 1.97inch, 53mm/ 2.08inch, 50mm/ 1.97inch, 53mm/ 2.08inch, 60mm/ 2.36inch. Package Includes: 1 Piece Diamond Grinding Bit Note: Please allow 1-2mm error due to manual measurement, pls make sure you do not mind before you bid Due to the difference between different monitors, the picture may not reflect the actual color of the item, pls understand, thank you