Brilliantly-colored "Dark Cap" Mathewson card, with sharp corners and a rich, blue and green background.  The tough American Beauty back adds to the desirability of the card, as does its sharpness.  American Beauty - backed T206 cards are traditionally cut more narrowly than other T206s, often leading to centering issues.  Such is the case with this example, centered to the far left of the canvas, to the point where the green border fram on the reverse is miscut.  The MK designation applied by PSA addresses this, as the card would otherwise grade EX due to square corners, bright borders, and the aforementioned vivid image.  A wonderful example of a very pleasing card, one of the more important Hall of Famers in the issue.