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 {HEAD ~ the minor ring segment} to the first and second arcuate elements at {TAIL ~ a location thereon proximate} to the opening to allow the minor ring segment to be displaced toward and away from the opening to expand and contract the ring shank 
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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 { HEAD ~ the minor ring segment } to the first and second arcuate elements at { TAIL ~ a location thereon proximate } to the opening to allow the minor ring segment to be displaced toward and away from the opening to expand and contract the ring shank
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