Forum:The thingie inside some Structure Decks

I just bought some old Structure Decks to add to my collection and when I opened them, there was a card-sized white piece of paper that had a small butt with a symbol. The symbol had a cross on a hand, maybe it mean "Do not open" but I was curious and tore the butt open anyway , inside the butt were aluminum strips or something.

So what is the use of this white paper ? Do the aluminum strips contain some hazardous chemicals ? Daywithoutgames (talk • contribs) 05:40, August 26, 2015 (UTC)