Mine Is stickered, that says, "Free Poster Inside". It does have a "Promo Copy Not For Sale" sticker on the back. Found a Big box of them, In a remote Charity. Our Radio station stopped giving these to Charoty, a long time ago. H.
I use a BIC Pen lid to get It back In. Put the top In the Flap (smooth side to the back) then slid the tab over the top, gently. And It should just slid In. I do this for all My Envelope sleeves. H.