Universal stainless steel weld-on o2 bung, could be welded to mild-steel, steel, and stainless steel piping. Great for custom oxygen sensor placement, place it where you like to prolong the sensor life and get better accuracy reading. Always great to have a spare o2 bung for your motorcycle, cars, hot rods, and scooter so that you could mount a wideband or air/fuel ratio gauge for monitoring and tuning.