The Hypro Diaphragm Repair Kit for the D30 (Kit1724) includes the 2 Desmopan Piston Diaphragms, the Buna Accumulator Diaphragm and the 4 Valve O-rings. It is recommended to change your diaphragms every year depending on your pump usage. Regular pump maintenance ensures a longer pump life and helps to eliminate sprayer down time. If you notice that your oil is a milky color that would most likely indicate a torn diaphragm, we suggest keeping a repair kit on your shelf for quick replacement. Hypro Diaphragm Pumps are designed so that the diaphragms are easily accessible and easy to replace, meaning you can do it yourself.