A temple endpiece includes a set of {HEAD ~ recesses} that engage {TAIL ~ the projections} formed on the lens 
engage
A temple endpiece includes a set of { HEAD ~ recesses } that engage { TAIL ~ the projections } formed on the lens
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH