... , eccentric drilling tools, standardized API system casings, bit shanks and casing tubes which are fit for hydraulic ... so on. We adopt numerical control process to all the accessory and apply it to the production ... R38,T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38 ... ,T38,T45,T51Down-The-Hole Tools1) DTH BIT---65MM to 254mm.2) DTH Hammer---76MM /90MM ...