PACK OF 3. Use this Comet 1800.0088 Buna Diaphragm to replace damaged or worn diaphragms on the Comet APS51, APS71, APS96, BP75, and IDS960 Diaphragm Pumps. A good indication that the diaphragms need replacing is if the oil in the sight glass is milky grey in color. Stop running the pump and replace the diaphragms immediately. Running a diaphragm pump with damaged diaphragms can damage the pump beyond repair.