At least some of the recesses 16′ are oriented such that their walls are substantially parallel to {HEAD ~ a major incident component} of {TAIL ~ an impacting force} 
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At least some of the recesses 16′ are oriented such that their walls are substantially parallel to { HEAD ~ a major incident component } of { TAIL ~ an impacting force }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL