... button bits, cross bits and chisel bits with (6, 7, 11, 12 degree taper).Bit diameter: 28mm- ... 57mm.3. Extension drilling toolsButton bit, face design: Flat face, ... (Threaded R32, R38, T38, T45, T51 ; bit diameter: 45mm-127mm);Couplings sleeves- manufactured with a middle ... Blast furnace tap hole drill tools. (Rod, Cross bits, button bits and X-type bits etc). ...