Faria Euro Black 2" Oil Pressure Gauge (100 PSI) [12845]Euro Black 2" Oil Pressure Gauge (100 PSI) Perimeter lighted Black dial with bold White graphics, Black aluminum bezel, contoured White pointer and flat glass lens. A pressure gauge operates by sending a low amperage current through the gauge's meter to ground via a sending unit with variable resistance. The resistance of the sending units increase or decrease with the changes in pressure, temperature, etc As the sender's resistance varies, the amount