Each hair retainer has a pair of {HEAD ~ opposing hinge ledges} at {TAIL ~ one end portion} thereof 
Each hair retainer has a pair of { HEAD ~ opposing hinge ledges } at { TAIL ~ one end portion } thereof
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH