The material of the inner liner is folded over at {HEAD ~ opposite edges} to form {TAIL ~ increased thickness margins} at opposite ends of the pack 
to form
The material of the inner liner is folded over at { HEAD ~ opposite edges } to form { TAIL ~ increased thickness margins } at opposite ends of the pack
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH