The problem is that {HEAD ~ the ferrule} may be optically mismatched with {TAIL ~ the mating adapter}  
optically mismatched with
The problem is that { HEAD ~ the ferrule } may be optically mismatched with { TAIL ~ the mating adapter }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH