The Spalding Gold Medal Dual-Face iron, stamped "DF" on the back of the blade, was sold by Spalding in 1913. The bottom third of the face is angled so that it has much more loft than the top of the face.  Hence the club was was said to have a dual face, although a dual loft face would have been more accurate. But I digress.  

The first dual face iron was devised by Thomas George Sharpe and patented in the UK in 1906.

In Sharpe's patent, he described the club as a backspin iron. "The object of this invention is to give increased accuracy in approaching the hole by causing the ball to roll as short a distance as possible after it touches the ground. To ensure this the face of the club...is made at two different angles, the upper part being perpendicular or nearly so, as an ordinary club, the lower part projecting forward at an angle to the upper part."

A review of Sharpe's iron that same year celebrated the club's ability to "loft shots over trees, hedges, or gorse-bushes" as well as "those little, slack-wristed well followed-through shots of 10-15 yards from rough grass up to the hole" and declared it as deserving a place in every player's bag. Seven years later, Spalding gave American golfer's their chance to add such a club to their kit. But, as would be easy to understand, the club met with a poor reception as it performed much worse than advertised. Consequently its extreme rarity when coupled with the dramatically inconsistent, nutso nature of its design helps make it such a great collectible.

Unlike Sharpe's original, the Spalding version has an unscored face. This particular iron measures 37" long and has been re-gripped, but the grip still matches up well. The original shaft is stamped "Spalding Bros / Gold Medal / Pat. Applied For."

TCA2 V1 P287