... by hollow drill steels, there are two shapes of extension rods, round type and hexagonal type,This hollow hole are usually named ... ,R28,R32,R38,T38,T45,T51,ST58,GT60 threads, and different length of rods are available from 600mm to 6400mm usually. Product ... -T511525T51-T511830T51-T512435T51-T513050T51-T513660 T51 Round Speedrod in factory prices and high quality