Compatible with all FAST Digital Air/Fuel Meters the FAST Air/Fuel Meter RPM Module monitors and records engine RPM data that can be overlaid with air/fuel ratio readings. It can be calibrated with the touch of a button and the module plugs in-line with your existing O2 sensor harness. The FAST Air/Fuel Meter RPM Module comes with everything you need including the installation CD communications cable USB cable adapter power source RPM module clip-on inductive pick-up and full instructions to get you up and running in no time.