A sucker rod is the mechanical link in a rod-pumping system that transfers motion from the surface pumping unit to the downhole rod pump. Supplied in standardized sizes and grades (commonly to API 11B), sucker rods are selected based on load, depth, deviation, corrosion conditions and fatigue life so the rod string can run reliably with fewer failures, wear issues and workovers.
link:http://www.octalpipe.com