A Nice Puzzle #2

The second contest has started! Same rules as the first- you get a chess problem, and have to name the key. If you've seen this before, no answering. no using anything except a board & pieces-no internet.

The winner again recieves a prize! :) I'll post when someone solves it.

EDIT: tushu & wisegi are the co-winners of contest #2! wisegi for being the first one to post the correct key in my blog, and tushu for being the first to send it to me via messaging. I now create another rule: you have to post the correct key in my blog first to win.