A retainer 1 wherein {HEAD ~ said entering nose portion} has {TAIL ~ a rounded exterior surface} and an inner enlargement 
A retainer 1 wherein { HEAD ~ said entering nose portion } has { TAIL ~ a rounded exterior surface } and an inner enlargement
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH