Euro Black 2 Cylinder Head Temperature Gauge (60 to 220Adeg F) with SenderPerimeter-lighted Black dial with bold White graphics, Black aluminum bezel, contoured White pointer, and flat glass lens.A temperature gauge operates by sending a low amperage current through the gauge's meter to the ground via a sending unit with variable resistance. The resistance of the sending units increases or decreases with the changes in pressure, temperature, etc. 2 - Hole Size: 2.0625 (53mm)Specifications:Anti-scratch glass lens12 VDC negative groundPerimeter-lighted Black dialCan be adapted for 24 VDC systemsFactory P/N GP9438*Sold as an Individual**Gauge Cover not Included