AEM Uego Wideband (Part Number: 30-4100). Using a wideband o2 sensor is the only real way to accurately monitor your air fuel ratio. Monitoring your air fuel ratio is the most important thing when making sure your car is tuned and runing safely and to its full potential. The AEM Wideband is one of the best and most trusted widebands on the market, it comes with a bosch wideband sensor and the trusty aem wideband controller. This fits in a standard 52mm gauge so you can install it in a gauge pod, or anywhere else for that matter. * Gives a Steady Reading, not a sweeping back and forth like a narrowband gauge * Standalone gauge, no computer or software is required * comes with Bosch o2 Sensor * 0.1 AFR Unit of Measure * Can be switch from AFR to Lambda