Spun Silver 2 Oil Pressure Gauge 80 PSI Perimeter-lighted Silver dial with bold Black graphics, polished stainless steel bezel, contoured Black pointer, and domed glass lens.A pressure gauge operates by sending a low amperage current through the gauges 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 senders resistance varies, the amount of current allowed to flow through