These FAST wideband air/fuel ratio analog gauge kits combine a super-fast and accurate gauge, a Bosch wideband oxygen sensor, and a stand-alone sensor control unit. The gauge kits can be mounted anywhere inside the interior, gauge pod, or dash. They're backlit for nighttime use and can be wired so that they're powered up whenever the engine is running. The FAST wideband air/fuel ratio analog gauge kits are ideal for monitoring the overall fuel tune of the engine when daily driving or racing at the track. They're great tools to have inside, where you can monitor the efficiency of your engine.