Mastro offered this 1979 Topps “Baseball Iron-Ons” Test Issue Keith Hernandez promotional piece in their Classic Collector Auctions Catalog in October 2007. After a lot of searching, I can’t find ANYTHING about it online or in The Hobby Library!
Unfortunately, the catalog was intended to augment an online auction, so there weren’t any item descriptions. On the net54Baseball forums, one collector wrote, “Topps would mock these up for internal use, creating Presentation Boards for one kind of pitch or another. Each piece was handmade by the New Product and /or Art Departments. I’ve not run across this one before but it’s pretty awesome.”
If you have any insight into this item or set, please get in touch with me.