According to one preferred embodiment of this invention, such as shown in FIGS 1 4, {HEAD ~ two layers} of flexible sheet 20 are connected along {TAIL ~ a longitudinally extending centerline} 60 
are connected along
According to one preferred embodiment of this invention , such as shown in FIGS 1 4 , { HEAD ~ two layers } of flexible sheet 20 are connected along { TAIL ~ a longitudinally extending centerline } 60
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH