12mm/18mm O2 SENSORS ADAPTOR. Precision manufactured with a ceramic body made of stabilized zirconium dioxide, surface coated with gas-permeable platinum electrodes and a porous ceramic to help prevent erosion due to contamination and particulates in the exhaust gases. Slow reading oxygen sensors can cause a drop in fuel economy of 10-15%, excessive exhaust emissions and poor drivability. Life expectancy of an average oxygen sensor in a properly tuned engine is typically 30,000-50,000 miles. Narrow band O2 sensors available in 12.5", 16", 16.25" and 22.25" overall lengths. Replacement Wide Band O2 sensor for aftermarket ignition tuners also available; overall length is 30.25". All sensors meet or exceed OE specifications. Made in the U.S.A. - Part Number - 1861-1108