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