{TAIL ~ The grid} is composed of {HEAD ~ glass} containing lead oxide, and eliminates the spacer material used in prior known grids, and is therefore, an air core grid 
{ TAIL ~ The grid } is composed of { HEAD ~ glass } containing lead oxide , and eliminates the spacer material used in prior known grids , and is therefore , an air core grid
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH