The end of the plug adjacent the threaded opening has a hexagonal square or circular exterior for {HEAD ~ reception} of {TAIL ~ a wrench} for connecting the plug to the flange opening 
The end of the plug adjacent the threaded opening has a hexagonal square or circular exterior for { HEAD ~ reception } of { TAIL ~ a wrench } for connecting the plug to the flange opening
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH