Dress White 2" Water Pressure Gauge (30 PSI)Perimeter-lighted White dial with bold Black graphics, White aluminum bezel, contoured Black pointer and flat glass lens.A pressure gauge operates by sending a low amperage current through the gauges&';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 change in pressure.2" - Hole size: 2.0625" (53mm)Specifications: Anti-scratch glass lens 12 VDC negative ground Can be adapted for 24 VDC systems Dual Scale - Metric and Imperial Factory P/N OP1006*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. Specifications: Gauge Type: Water Pressure Series: Dress White Voltage - Input Range (Volts): 12/24 V Gauge Size: 2" Box Set: No Box Dimensions: 5"H x 5"W x 6"L WT: 0.7 lbs UPC: 759266131088 Quick Guide (pdf)