Ok, so those clamp-on style O2 sensor bungs are cool if you are doing a quick installation and don't have access to a welder.  But are you going to leave your system that way?  No, we didn't think so.  Spring for the couple of bucks to get a weld-in bung and get your sensor installed permanently--the way it was meant to be.  Choose from either mild or stainless steel.  Fits virtually all screw-in style O2 Sensors.