at least one thermal exchange means composed of parallel inner and outer plastic sheet means separated by {TAIL ~ a plurality} of {HEAD ~ parallel flat ribs} oriented normal to said sheet means and fused to said sheet means to form a plurality of parallel channels 
at least one thermal exchange means composed of parallel inner and outer plastic sheet means separated by { TAIL ~ a plurality } of { HEAD ~ parallel flat ribs } oriented normal to said sheet means and fused to said sheet means to form a plurality of parallel channels
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH