3" AEM No-Weld O2 Sensor Mount - Our No-Weld O2 Sensor Mount enables users to mount an O2 sensor without having to weld a sensor bung onto the exhaust. Simply drill a hole in the exhaust, install the gasket, and bolt the clamp.  It's that easy!  The 3" mount will fit exhausts from 2.75" to 3" in diameter.