... bits, buttons bits, DTH bits with high, medium and low air pressure, symmetric drilling tools, eccentric drilling tools, standardized API ... system casings, bit shanks and casing tubes which are fit for hydraulic drilling ... R28,R32,R38,T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38,T38, ...