The plug is further provided with an axial passage way 18 communicating with {HEAD ~ the hexagonal square or circular wrench end} of the plug at {TAIL ~ one end} and terminating adjacent to and just short of the threaded end 
The plug is further provided with an axial passage way 18 communicating with { HEAD ~ the hexagonal square or circular wrench end } of the plug at { TAIL ~ one end } and terminating adjacent to and just short of the threaded end
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH