Chesapeake Black 2" Water Temperature Gauge (100-250F)Perimeter-lighted Black dial with stylish Blue and White graphics, polished stainless steel bezel, contoured White pointer and domed 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 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: Anti-scratch glass lens; Plastic Cases for corrosion resistance and long life; 12 VDC negative ground; Can be adapted for 24 VDC systems; Dual Scale - Metric and Imperial; Factory P/N GP9142*Sold as an Individual**Gauge Cover not IncludedThis product may not be returned to the original point of purchase. Please contact the manufacturer directly with any issues or concerns. - cis2:mm5mnJlm -Specifications: Gauge Type: Water Temperature; Series: Chesapeake Black; Voltage - Input Range (Volts): 12/24 V; Gauge Size: 2"; Box Set: No; Box Dimensions: 4"H x 4"W x 5"L WT: 0.3 lbs; UPC: 759266137042; Quick Guide (pdf)