Faria Beede Instruments 2" Hourmeter Digital 10000 Hours 12-32VDC Dress White - Retail Package. 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. Specifications for Faria Beede Instruments 2" Hourmeter Digital 10000 Hours 12-32VDC Dress White: Manufacturer: Faria Beede Instruments Color: White Features of Faria Beede Instruments 2" Hourmeter Digital 10000 Hours 12-32VDC Dress White Wide range of scales Available for gas or diesel engines Multiple signal sources Anti-scratch glass lens Color: Dress White Package Contents: Faria Beede Instruments 2" Hourmeter Digital 10000 Hours 12-32VDC Dress White Faria Beede Instruments 13130: 2" Hourmeter Digital 10000 Hours 12-32VDC Dress White - Retail Package