In a second preferred embodiment, a minor ring segment having a pair of externally groove sidewalls is provided in conjunction with a linkage pivotably connecting the minor ring segment to the first and second arcuate elements at a location thereon proximate to {HEAD ~ the opening} to allow {TAIL ~ the minor ring segment} to be displaced toward and away from the opening to expand and contract the ring shank 
to allow
In a second preferred embodiment , a minor ring segment having a pair of externally groove sidewalls is provided in conjunction with a linkage pivotably connecting the minor ring segment to the first and second arcuate elements at a location thereon proximate to { HEAD ~ the opening } to allow { TAIL ~ the minor ring segment } to be displaced toward and away from the opening to expand and contract the ring shank
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