Extension drill rod 1)thread: R22 R25 R28 R32 T38 T45 T51 ... :280mm-6400mm Extension drill rodt45 extension rodThread: R32, R38, T38, T45, T51Top Hammer / Production Rock Drilling Tools:Coupling Sleeves, Thread Button Bits ... , Extension Rod, Shank Adaptors.Extension drill rodD: 32,38,45,51mmL: 800 ...