Universal Narrowband Air/Fuel Ratio Gauge (B7008W) by Intellitronix. Diameter: 2-1/16". Display Type: LED Digital Bargraph. Bezel Finish: Black. Air/Fuel Ratio Narrowband LED Digital Bargraph Gauge is the ultimate way to monitor the ratio of fuel to air in your vehicle’s engine and keeps your engine purring with a lean, rich and stoich fuel mixture. Avoid extensive damage to your vehicle’s engine by running too lean. Now you can really watch the ratio of fuel to air in your vehicle with the Intellitronix super bright LED digital air/fuel ratio bargraph gauge. It is accurate, super bright, and intelligent all in one