1.coal mining tools 2.ore mining, many type 3.good price,high quality ... hex. Bit diameters include 20-42mm.2. Tapered drilling tools (Tapered Drill Steel)Including:Shank H22x 108mm, (6, ... kinds of casing bits for shield machine and construction tools.7. Round road planning bit for road milling ... 33mm, 38mm, etc.8. Blast furnace tap hole drill tools. (Rod, Cross bits, button bits and X-type bits ...