... made by hollow drill steels, there are two shapes of extension rods, round type and hexagonal type,This hollow hole are ... be used for connecting coupling sleeves, shanks or bitsUsually for extension rods, there are R22,R25,R28,R32,R38,T38,T45 ... & Round MF rodsRd51T51-T513660T51-T511220T51-T511525T51-T511830T51-T512435T51-T513050T51-T513660 Extension Rod R32 (1 1/4'')round Rod in factory prices