Sucker rod:A special steel pumping rod.
Several rods screwed together make up the mechanical link from the beam pumping unit on the surface to the sucker rod pump at the bottom of a well.
Sucker rods are threaded on each end and manufactured to dimension standards and metal specifications set by the petroleum industry.
Lengths are 25 or 30 feet (7.6 or 9.1 meters); diameter varies from 1/2 to 1-1/8 inches (12 to 30 millimeters).
There is also a continuous sucker rod (tradename: corod).