{TAIL ~ A method} 1 or 2, including {HEAD ~ blending} of the material with a foaming agent which will chemically decompose during the extruding 
{ TAIL ~ A method } 1 or 2 , including { HEAD ~ blending } of the material with a foaming agent which will chemically decompose during the extruding
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH