The listing, Sheet: "Linn's Stamp News" Seals has ended.
"COLLECT STAMPS It's Fun!" seals were a premium sent to subscribers to 'Linn's Stamp News', a newspaper on stamps and stamp Collecting, to promote the hobby.
These are unused with full gum; mint actually with the flaw of the folding when they were mailed.
The sheet has a plate number in the lower right margin of: LJSP01
These came folded to fit in a letter size envelope, as shown in my 3rd image. That's how they will be mailed to you, also.