What camera is this tiny lens board for?

I have been saving up to buy a tele-xenar 360mm, and while I was in the US one came up on eBay, but from a non-photographer seller. Since I was in the US and had the minimum bid I went ahead ($162), and no one else bid so I won it. Luckily, everything seems pretty good on it, but it came with a tiny lens board like none I have ever seen before. It is 3" x 3" (76mm) with rounded corners. I have no use for it so thought I would pass it on. Here is is with the 360mm flange still mounted:
Attachment 133955

Here it is without the flange:

Attachment 133956

And here is the back. It has a little tab sticking out:

Attachment 133957

Any idea what it fits? I'm guessing some sort of press camera, but I only know the graphic board.

Graflex?

Maybe a Busch pressman 4x5

Busch Pressman D. The threaded tang at the bottom is the giveaway.

Yes, it looks like Busch Pressman D to me also.

Thanks guys! I will now pass it on.