... 1.For stones and glass core drilling 2.High drill accuracy 3.Fast drilling speed 4.Safelong life Best quality ... Diamond threaded shank Drill Bit for glass introduction:Threaded shank Drill Bit : using high quality steel substrate, head ... : durable to polish and not crack, high efficiency, long life, drill 4000-5000 holes/pc2.Main Market: Europe market.3. Application ...