Spun Silver 5" Multifunction 3-in-1 Combination Gauge with Tachometer, Fuel & VoltmeterPerimeter-lighted silver dial with bold black graphics, polished stainless steel bezel, contoured black pointer, and domed glass lens.Electronic tachometers work by counting pulses generated by the ignition system, alternator, tach signal generator or magnetic pickup sender. The tach is hooked up to +12vDC, Ground and one of the signal sources listed above.By selecting the right tach and setting the switch on the back to the correct position you let the tachometer know how many pulses are sent per each engine revolution.A voltmeter indicates the battery voltage and the general condition of the battery charging system. The meter requires no warm-up and indicates voltage changes instantly.Multi-Function Gauge Displays:Fuel (E-1/2-F)Voltmeter (10 - 18 VDC)Tachometer (0 - 7000 RPM)5" - Hole size: 4.375" (112mm)Specifications:Scratch Resistant LensPolished Stainless Steel Bezel12 VDC Negative Ground Illuminated OEM P/N 13982, 172663 or 61957