Kronos 4" Tachometer - 6,000 RPM (Gas - Inboard & I/O)Polished Stainless Steel bezel, flat glass lens, perimeter lighted spun aluminum dial with Gold and Black graphics. Gold increments and Logo on dial are Embossed. All instruments include two piece Newport pointer with White hub. 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.4" - Hole size: 3.375" (85mm)Specifications: Flat Scratch Resistant Lens Polished Stainless Steel bezel LED Illuminating around the Perimeter of the Dial Newport style White Pointer Factory P/N TC9983*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: Tachometer Series: Kronos Voltage - Input Range (Volts): 12/24 V Gauge Size: 4" Box Set: No Box Dimensions: 5"H x 6"W x 6"L WT: 0.7 lbs UPC: 759266390041 Quick Guide (pdf)