... , symmetric drilling tools, eccentric drilling tools, standardized API system casings, bit shanks and casing tubes which are fit for hydraulic drilling ... the high quality and reliability of the products.Tapered Drill BitType --Chisel Bits / Cross Bits / Button Bits Diameter---28mm,30mm 32mm,34mm ... ,R28,R32,R38,T38,T45,T51Down-The-Hole Tools1) DTH BIT---65MM to 254mm.2) DTH Hammer---76MM /90MM /110MM 3 ...