These universal low pressure switches can be used to alert of a drop in oil pressure. Connection is via a single spade connector and the unit can be fitted into the engine block via a range of thread adaptors (available separately)Fixed 20 Psi switch or adjustable 0-50 Psi (preset at 20 Psi).1/8" NPT threadSetting the adjustable switch: Remove the rubber plug in the top of the sender. At the bottom of the hole is a hex nut. Use a 7/32 allen wrench to adjust. Turn clockwise to increase pressure, counter-clockwise to lower. Replace rubber plug when done.An easy way to adjust the switch/sender is to turn the motor over with the starter-ignition off. The oil or fuel pressure will rise slowly.Note the pressure where the light goes out. Adjust as needed and retest. If you try to do this by starting the motor the pressure will rise so fast you may not be able to see the set point.