The material of {HEAD ~ construction} of {TAIL ~ the grid walls} of this invention is glass with a high content of lead oxide, or other high atomic number oxide 
of
The material of { HEAD ~ construction } of { TAIL ~ the grid walls } of this invention is glass with a high content of lead oxide , or other high atomic number oxide
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH