According to {TAIL ~ one preferred embodiment} of the invention, a ring top having first and second slider members affixed thereto is disposed within said opening in a manner such that {HEAD ~ the first and second slider members} are slideably mounted within interior groove portions in each of the first and second arcuate elements to dispose the ring top in said opening 
According to { TAIL ~ one preferred embodiment } of the invention , a ring top having first and second slider members affixed thereto is disposed within said opening in a manner such that { HEAD ~ the first and second slider members } are slideably mounted within interior groove portions in each of the first and second arcuate elements to dispose the ring top in said opening
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