{HEAD ~ The rings} are preferably formed as open cylinders having a series of axially extending slits through {TAIL ~ the wall} thereof 
{ HEAD ~ The rings } are preferably formed as open cylinders having a series of axially extending slits through { TAIL ~ the wall } thereof
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH