This Switch will accept an input rpm signal from a coil negative terminal (for stock ignitions), a tach output from an ignition control, an ECU tach output or even a 5 volt tach signal. Another great feature is that no rpm modules are needed! The rpm activation points are programmed by simply scrolling through the LED display to your desired rpm amounts.The switch has two outputs one Normally Open, the other is Normally Closed. It can be programmed from 200 rpm to 15,000 rpm in 100 rpm increments. It can be used with an input voltage of 9-18 volts.