Need help identifying promo variant of Flash #231

[Kelson]

Someone recently sent me a scan of a cover from a variant edition of last summer's Flash #231 (the relaunch with Mark Waid and Daniel Acuña. It's the Doug Braithwaite cover, except the art is entirely gray. It looks like it may just be the pencils.

http://www.hyperborea.org/flash/images/c3/cover-f2-231-gray.jpg

The rectangle at the lower left says, "Not for sale. For promotional use only"

Does anyone know where/when this was handed out? Was it passed out at a convention? Was it sent to retailers or reviewers?

Thanks in advance!

[Kelson]

Answer found! Fastest over at Comic Bloc identified it as a retailer incentive, and pointed me to a couple of eBay auctions. From there I identified it as a RRP edition handed out at last year's Diamond Retailer Summit.