Product:Round drill rods Thread type:R25,R28,R32,R38,T38,T45,T51 ... ,Rd45,Rd51 Length:1000-3660mm BETOPPER ----Thread drill rodsThread drill rods are made by hollow drill steels, there are two shapes:round type ... be used for connecting coupling sleeves, shanks or bitsUsually for extension rods, there are R22,R25,R28,R32,R38,T38,T45 ...