The 1906 Ullman's "Art Frame" series of postcards are a rare and valuable set of cards, most of which were produced to commemorate the New York Giants' 1905 World Championship.  Each of the cards feature a black and white photograph inset into a wood-grain "frame."  The Ullman Manufacturing Company of New York began as a publisher of lithograph prints and eventually began producing postcards and greeting cards.  Their postcards were known for their high-quality printing and heavy paper.

The Ullman baseball postcards are found with both green and brown tinted frames.  As of today, 13 different cards are known, but the cards are rare enough that it is considered likely that there are cards in the set that have yet to be discovered.  

Easily the key card in the issue, that of Hall of Fame pitcher Christy Mathewson.  Graded PR 1 by SGC, this is one of just eight examples of this rare card to have been graded by SGC (we have reason to believe that this particular example was counted twice, so there are just seven).  Boasting a clean image, the card, like most of the other known surviving examples, exhibits edge and corner chipping, along with some horizontal creasing that does not interfere with the eye appeal of the image despite being clearly visible.  Postal use lends authenticity to the grade.  Simply an outstanding, rare, and extremely desirable postcard, easily one of the more important commercially-issued baseball postcards.