The ribbon has a small thickness to prevent {HEAD ~ obstruction} of {TAIL ~ the elements} bordering the top flange and the upper surface of the top flange 
of
The ribbon has a small thickness to prevent { HEAD ~ obstruction } of { TAIL ~ the elements } bordering the top flange and the upper surface of the top flange
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH