If your application needs to have the oxygen sensor angled into the exhaust pipe rather than perpendicular, this steel weld-in bung will do the trick. The more streamlined positioning of the sensor may even reduce exhaust back-pressure and increase performance. It fits the common 18x1.5mm oxygen sensor thread, but it is cut on a 45 degree angle. Fits any standard oxygen sensor including the Single-Wire Oxygen Sensor (Part No. 3882) and the Bosch LSU 4.2 Wideband Oxygen Sensor (Part No. 3877-Sensor). Oxygen sensors sold separately.