M/F Speed Rod - Chinese The most popular drilling rods

（1）Thread: R22, R25, R28, R32;

（2）Rod size : hex.22mm, hex.25mm,hex.28mm, hex.32mm, hex.35mm;

（3）Length: 600mm-8000mm;

（4）Package: in wooden case or in bundles;

（5)Supply ability: 10000pcs/month;  

Speed rods are made by hollow drill steels; there are two shapes of extension rods, round type and hexagonal type. This hollow hole are usually named flushing hole, used for transmitting water or air during drilling，And the threads can be used for connecting couplings, shanks, couplings or bits. Usually for extension rods, there are R22, R25, R28, R32 threads, and different lengths of rods are available from 600mm to 8000mm usually.