It also has {HEAD ~ an end bar} of hafnium secured to {TAIL ~ the bottom plug} by a purely mechanical connection 
It also has { HEAD ~ an end bar } of hafnium secured to { TAIL ~ the bottom plug } by a purely mechanical connection
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH