13#ceramistpalace5 `$ M& C: a8 w9 H# s+ ?$ T% }
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It's two layers of greenhouse plastic that is inflated with air.
15#ceramistpalace ' ?3 E6 H$ z) @8 h v, {9 z" a- u' l 5 O) g5 [* U( U5 T4 E ; Q- M J$ m6 v$ nMy husband seals the plastic layers himself, then use a small fan to blow air between the two layers. The plastic can only be bought at Horticulture supply stores.