AEM's X-Series Wideband Air/Fuel Ratio Sensor Controllers are built upon unique, patented X-Digital technology (Patent 9,575,030), making them the fastest responding wideband air/fuel ratio controllers in independent testing*. AEM co-developed its new wideband sensor with global automotive supplier FAE, culminating in a new design that has a faster response time and is less prone to failure in high performance vehicles. It can be used on EFI or carbureted applications, and in fuel systems using gasoline (including leaded race gas), methanol, ethanol, diesel, propane, and CNG. The X-Series Wideband AFR Gauge (PN AEM 30-0300) mounting surface measures 2 1/16th-inch (52mm) in diameter and features a modern center display that is 87% larger than the 30-4110 AEM Wideband Gauge's center display. Its slim depth (less than one inch overall) dramatically increases its application base and potential mounting locations. The AEM Wideband X-Series AFR Gauge has a user configurable display via buttons on the gauge face that allows you to change between AFR, Lambda, or O2%, change the center display to three or four digits, perform a free-air calibration if desired, and change the CAN message ID when linking multiple X-Series Wideband Controllers.