I'm not sure man, it was this plastic that we used for solar boxes. we had to design a box with a certain sized sheet of insulation, black spray paint, and clear plastic wrapped over the top to let light in. they got up to 140-150 degrees on a 46 degree day. I asked if he had any plastic left over and he gave me the rest of the roll. I'll have to ask him when I go back. problem is we're on spring break
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