With no laptop required, FAST has developed three simple, easy - to - use airfuel meters for gasoline, diesel and EthanolMethanol (E85) fuels. Available in single or dual sensor units, these meters give tuners the power to read two wide - band O2 sensors individually or average them together for maximum accuracy of the engines airfuel ratio reading. The FAST Air Fuel Meters include several enhanced capabilities, including the built - in data logging capability that plays back recorded information on a lighted, full graphical display screen rather than using a laptop computer. Additional features include outputs for external data loggers, digital gauges, as well as a narrow - band simulator function that allows you to feed your engines computer a factory signal while using the wide - band sensor for airfuel measurement.