Railway and Highway Tunneling Borehole Drilling Thread Drill Extension Rods (MM/MF) Product Name:extension rodsDescription:extension rodsThread drill rod made with best quality carbon steel bar,through heat treatment like Atlas.Material:carbon steel barMOQ:No MOQ required for testing and trial orderBody TypeRound shape and hexagonal typeThread typeR25,R28,R32,R38,T38,T45,T51Diamet