According to one preferred embodiment, {HEAD ~ a ring top} having first and second slider members is disposed within the opening with the first and second slider members slideably mounted within interior groove portions in {TAIL ~ each} of the first and second arcuate elements 
According to one preferred embodiment , { HEAD ~ a ring top } having first and second slider members is disposed within the opening with the first and second slider members slideably mounted within interior groove portions in { TAIL ~ each } of the first and second arcuate elements
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH