Extension drill rod 1)thread: R22 R25 R28 R32 T38 T45 T51 ... type: hex or round(plain) 3)length:280mm-6400mm Extension drill rodt45 extension rodThread: R32, R38, T38, T45, T51Top Hammer / Production ... :Coupling Sleeves, Thread Button Bits, Extension Rod, Shank Adaptors.Extension drill rodD: 32,38,45,51mmL: 800-6100mmThread: R32, R38, T38 ...