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. 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.
Wide range of scales
Available for gas or diesel engines
Multiple signal sources
Rugged, Reliable construction