The Medco Aspirator IV utilizes two advanced, state of the art positive displacement pumps. These dual headed pumps relieve back pressure to allow each individual pump to pull against the patient so that a deep vacuum is quickly reached and maintained. If one pump should go down, the other three will continue to function independently. Combined with a super quiet muffler and insulation system, the positive displacement pumps used in the Medco Aspirators are the quietest on the market. All Medco Aspirators come with a limited 5 year warranty on all parts and labor.