j. ballman, author of the full-color guide to marvel silver age collectibles
generously provided this information about the pin-up: "before the suffocating
popularity that hit marvel in the mid-1960s, fans could write in to get autographs
or sketches from their favorite artists and writers. as marvel increased its titles
and its readership, however, the workload of marvel employees made it impossible
to reply individually to each of its many fans. this pin-up of one of marvel’s most
successful characters at the time was the solution to answering fan mail (there
was also a fantastic four pin-up). the pin-ups were printed in such a way that it
was hard to tell they weren’t original art to the untrained eye, and it was even
more difficult to tell whether the signatures were hand-signed or pre-printed.
the pin-ups were given out to fans visiting the office or as responses to fan mail.
it is a fact these were in circulation well before the m.m.m.s. began in late 1964."

image of original pin-up courtesy of j. ballman