SP-2Z-12F Nason low oil pressure switch, commonly used on the DMT generatorsSP 2Z 12F Nason low oil pressure switch, this is a NO, NC switch. This switch is a "falling type switch" that is triggered at 12 psi This switch has been updated to part number MM 2C 12F AT and is physically different, the main difference is that the new switch gives you a choice between normally open and normally closed contacts. On the DMT application you will use normally closed contact (NC) and the common (C) terminals. The 3rd picture will be