When I picked the Braves photos (see last post) I also picked up a rare 1982 Topps Dungeon Master Screen. Oh, they'll tell you that it is some sort of sell sheet, a promo given to the dealers to get them and their customers excited about the upcoming card set.
We really know what it is.
Here's the closeup of the ad for Collecting Boxes.
And the back of that "card" is the add for the Card Locker.
I've never seen the Boxes, the Locker or the DM screen before.