These are the 6½" x 10" Masterprints, a set of nine large cards each of which collected one of the three-by-three-grid combined scenes of Bagley artwork from the 1994 Fleer Amazing Spider-Man trading card set. The 81 cards reproduced in these Masterprints were the first cards in the original set, i.e. numbers #1-81,
You could get these via mail-in. One mail-in for $3.99 + $1.00 shipping got you a set of three Masterprints. Also, a single Masterprint was provided as a bonus in each case of 20 boxes shipped to distributors.
I have also seen mention of a "Masterprint Mini-Poster". However I cannot find any photos of such a thing, and in any case we don't track posters in the SpiderFan database.