The Aeroflow Performance digital Air Fuel Ratio gauge kit has been designed for you to provide good insurance for your engine to ensure it does not run too lean while driving. Accurate AFR data is critical when tuning an engine. Running rich can cause a loss in power, while running too lean may result in serious engine damage. Using the Aeroflow Performance wideband AFR gauge with a 5-wire heated wideband LSU 4.9 sensor during the tuning process allows you to monitor AFR's and adjust tuning parameters to optimize them for maximum power and efficiency. Featured with this wideband is a blue LCD with a digital readout in the centre of the gauge, and a bar-graph style LED';s around the outside of the gauge that change from green (rich) to yellow (optimal) to red (lean) for immediate reference to the AFR.