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