... :343,348,370mm Purpose:It is mainly used to right the rod in side-wearing well, especially in above-neutral point ... coupling, tri-sawtooth ring, centralizing case, nine sawtooth ring, pup joint and so on.Traits:Simple structure, convenient usage, long time ... during operating, must slow down the speed in order to avoid scratching the surface on the joint between the rod and the well mouth. SUCKER ROD ...