... 370mm Purpose:It is mainly used to right the rod in side-wearing well, especially in above-neutral ... -sawtooth ring, centralizing case, nine sawtooth ring, pup joint and so on.Traits:Simple structure, convenient usage, long ... lower cost and so on.When dropping the oil rod during operating, must slow down the speed in ... to avoid scratching the surface on the joint between the rod and the well mouth. SUCKER ...