Spun Silver 2" Water Temp Gauge (100 - 250° F) Perimeter-lighted Silver dial with bold Black graphics, polished stainless steel bezel, contoured Black pointer, and domed glass lens.A temperature 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 of current allowed to flow through it to ground changes and the meter deflects, showing the temperature.2"- Hole Size: 2.0625" (53mm) Specifications:Domed, Scratch Resistant LensStainless Steel BezelLED Illuminating around the Perimeter of the DialDual Scale - Imperial and MetricFactory P/N GP9428*Sold as an Individual**Gauge Cover not Included