13#ceramistpalace + J1 X! g4 r, v: g. K: L- s W+ N @. P/ h& }* g. a. O" a O 3 C! F E& o9 J& [9 e/ YIt's two layers of greenhouse plastic that is inflated with air.
15#ceramistpalace ' D( F9 \# [+ Y, K, z 9 B% s5 V& f+ L' p 7 @& v' x( @, VMy 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.