... Drill Steel)Including:Shank H22x 108mm, (6, 7, 11, 12 degree taper) taper rods in most ... 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, Drop centre, Normal and ... U92, U94, U95, U118 and coal bolting bit and coal bolting rod.6. All kinds of casing bits ...