I have used these envelopes and love them!!!! It has a 12x12 pocket for your large (long) sticker sheets and smaller pockets for your smaller sticker sheets.
I use these envelopes to organizer my themes (baby, wedding, children, family, etc.). So since I do that, I actually put more than stickers in it. I will put in die cut and vellum tags too. It great for all that not just stickers. I have even put in 1 or 2 12x12 papers that go with my themes.
A definate buy if you are looking to orgainzer your themes in an easy way.