... 2.Tapered drilling tools(Tapered Drill Steel)Including:Drill rods with Shank H22x108mm,(6,7,11,12 degree taper) taper ... T45,T51, bit diametre:45mm-127mm);Couplings sleeves-manufactured with a middle stop to prevent walking along the thread. Include couplings sleeve ... R32,R38,T38,T45,T51)Shank adapters-carburized and manufactured with tight tolerances and controlled straightness.4.Down the hole hammers ...