... - Vacuum brazed diamond graver/ grinding pin/ point bit Product specification:size C11, shank 12mm, ovl 60mm, cel 12mm,it is better ... around 10pcs for trail. When you use it , if you have any questions, please feel free to write it to me. Only set right ... 25--32 hours. IF you dont know how to use it , please contact me before use it. Softwares and CNC engraving machin, stone ...