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