... deformation 4 long life Diamond glass core drill bits are used to drill glass,ceramics, porcelain, ceramic, porcelain tile, limestone, slate ... ,75mm,90mm,95mmService life: can dig 4000 to 8000 holesDrill bit type:1. Straight shank2. Cone/taper shank3. Threaded shank( male ... drill bits can be customized.This is the diamond drill bit we are producing: Other abrasive products we produce is as ...