The RDS Cast Iron Wireline or Mechanical Set Cement Retainers are rugged, and proven. Both models feature a positive, pressure balanced sleeve valve which is opened or closed simply by lowering and raising the tubing.  Positively secured packing element and one piece slips combine to premature setting due to well debris or rough handling and assures protection from the hazards of high speed running in the well.  The metal back-up rings prevent extrusion of the rubber at high pressures and temperature.  Because of their design, the metal to metal contact developed by  these back-up rings is made more secure by pressure increases.  An internal ratchet lock ring retains the dynamic force induced in the retainers during the setting operation.  This simple mechanism assured continued compression of the packing element regardless of pressure differentials.  Case hardened, one piece slips, designed to bite into the hardest casing are locate at each end of the retainer.