Dress White 2 Water Temperature Gauge 100-250FPerimeter-lighted White dial with bold Black graphics, White aluminum bezel, contoured Black pointer and flat glass lens.A temperature 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 it t