Another mysterious Pro Set prototype issue. Meant to sample their up-and-coming, premium line of card, Platinum, this promo features former Cincinnati Bengals running back, James Brooks. This one looks like it was an in-hand sample, photocopied for use in the ad, rather than just an image on a sheet sent to the dealer:
Obviously, the backs of 1991 Pro Set Platinum went through a few design changes. What you see above, is the only reference for the card I have ever been able to find. Certainly, at least that copy must exist out there somewhere, but as of 2010, not a copy has surfaced on any of the usually channels.
PS: Check out those case prices. They are extremely limited!!