... symmetric drilling tools, eccentric drilling tools, standardized API system casings, bit shanks and casing tubes which are fit for hydraulic drilling ... 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 /110MM 3) Face ShapeConvex--- ...