a) said clamping lock housing and said {TAIL ~ central retaining element} are made of {HEAD ~ plastic} 
a ) said clamping lock housing and said { TAIL ~ central retaining element } are made of { HEAD ~ plastic }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD