The K&N Air / Fuel Monitor is a precision instrument designed to help performance enthusiasts calibrate an optimum air/fuel mixture ratio. This device will work on carbureted, injected, supercharged or turbocharged engines using unleaded gasoline, alcohol, propane or nitrous oxide. It will not work with nitromethane or diesel fuels. Using the instrument to monitor the engine’s air/fuel mixture ratio, a tuner can adjust for power, economy and/or improved drivability.