{HEAD ~ A typical E glass composition} is about 53.5% by weight silicon dioxide , {TAIL ~ about 8% boron oxide} , about 14.5% aluminum oxide , about 21.7% calcium oxide , and about 1.1% magnesium oxide  
is
{ HEAD ~ A typical E glass composition } is about 53.5 % by weight silicon dioxide , { TAIL ~ about 8 % boron oxide } , about 14.5 % aluminum oxide , about 21.7 % calcium oxide , and about 1.1 % magnesium oxide
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL 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 OTH