... symmetric drilling tools, eccentric drilling tools, standardized API system casings, bit shanks and casing tubes which are fit for hydraulic drilling ... forging hammer, seal chamber furnace lines, precision machine tools and so on. We adopt numerical control process to all the accessory and ... R28,R32,R38,T38,T45,T51Face Shape---Plate, Concave, Convex.Bit Shank & Coupling sleeve---R22,R25,R28,R32,R38,T38, ...