a) an elastic support exhibiting {HEAD ~ a resilience} of {TAIL ~ at least 80%}; and 
a ) an elastic support exhibiting { HEAD ~ a resilience } of { TAIL ~ at least 80 % } ; and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH