http://ecomodder.com/forum/showthrea...tml#post151129
This was my attempt at explaining the plastic.
I believe this was the exact item I purchase in black 4 mil thick:
Film-GardŽ Polyethylene Sheeting in Various Sizes & Colors - Polyethelene Sheeting - Ace Hardware
Coincidentally, I recently had to destroy the cap and send it on its way to a new life as something else. The plastic was amazingly intact considering I thought it would only last for a year or so.