{HEAD ~ A layer} of a resilient and crush resistant polymer is interposed horizontally at any level through {TAIL ~ the entire thickness} of the material of said elements 
is interposed horizontally through
{ HEAD ~ A layer } of a resilient and crush resistant polymer is interposed horizontally at any level through { TAIL ~ the entire thickness } of the material of said elements
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH