According to {HEAD ~ 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 the first and second slider members are slideably mounted within interior groove portions in {TAIL ~ each} of the first and second arcuate elements to dispose the ring top in said opening 
According to { HEAD ~ 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 the first and second slider members are slideably mounted within interior groove portions in { TAIL ~ each } of the first and second arcuate elements to dispose the ring top in said opening
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