Posted By: 
Dan MathewsonI won this card recently at an eBay auction.  The seller described it thus:
Christy Mathewson -- Pinkerton Type Photo Postcard.
Similar to T5 Pinkerton but not mounted on cabinet back. Reverse is blank. It measures 84mm x 139mm. I understand these might have been made a little later than the original Pinkertons, possibly around 1918. This card is numbered 251.
I was going to try to get a scan of it on here, but I don't even see that option on here anymore.  The acution maybe up a little longer, here is the link.
Does anyone here have any idea what this really is?  I have done some research, but I can't come up with the actual card or issue.  I'm quite curious.  Thanks.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1867557843&rd=1 
-dan