A feature of the invention relates to the material used on {HEAD ~ the contacting surfaces} of the base member and {TAIL ~ the flaps} 
of
A feature of the invention relates to the material used on { HEAD ~ the contacting surfaces } of the base member and { TAIL ~ the flaps }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL