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