1) CD200 for diaphrgam protector, 2) CD401 for piston seperator 3) Use for repair piston seperator. Diaphragm Rubber is a replacement part,it is widely use for diaphragm protector and piston isolators, it is easily break during the operation.CD200 diaphragm rubber is use for diaphragm protetor.CD401 diaphrgam rubber is use for 1:1 piston seperator