... -resisting, polishing effect is good, stable quality, good diamond,Positioning hole,Cooling holeDescriptionDiameter: 5mm - 100mm.Total length ... shank2. Cone shank3. Threaded shankModel1.Sintered diamond drill bit.2.Electroplated diamond drill bit.CompanyEstablished in 1990,Zhecheng ... production and sales of various kinds of synthetic diamond and diamond tool,glass tools,which keep ahead in Chinese ...