Get the information and feedback you need by using the Faria 32840 Euro Tachometer Gauge 7000 RPM with Hourmeter. The unit works by counting pulses generated by the ignition system alternator tach signal generator or magnetic pickup sender. The Faria tachometer is hooked up to +12vDC ground. By setting the switch on the back to the correct position you can let the tachometer know how many pulses are sent per each engine revolution. It s designed to be compatible with all types of different vehicles. The unit measures 4 and can make a useful addition to the rest of your car accessories and tools.