DOLPHIN RO WATER PURIFIER MODEL COVER. HEAVY MATERIAL OF COVER. HIGH QUALITY CHAIN USED IN COVER. THIS COVER PREVENT THE SYSTEM FROM DUST, OIL, COLOR AND INSECTS. THIS COVER MAY INCREASE LIFE OF CABINET OF SYSTEM. It is recommended that the flow restrictor is replaced each time an RO membrane is replaced in order to keep your system working at optimum performance, as scale build up can occur and clog the capillaries, Flow Resistor will create back pressure on the membrane and allow the membrane to produce more purified Pure,Tasty,Sweet water.