{HEAD ~ Such materials} include {TAIL ~ metals} such as an aluminum alloy or stainless steel, a polymer such as Acetal and composites 
{ HEAD ~ Such materials } include { TAIL ~ metals } such as an aluminum alloy or stainless steel , a polymer such as Acetal and composites
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH