FJO wideband O2 tuning device is what all the top tuners use for the most acurate results. The tuning tool gives exact air fuel readings without any delays as opposed to standard gauges. Road tuning is better then dyno tuning because a true setting is taking place. Therefore to get appropriate results to dial in your air fuel readings, you must have this tool with ANY fuel management device. Includes the A/F probe, power supply, and gauge for easy mounting in vehicle. For more questions please contact us.