Covered under Edwin McClain’s December 1928 US patent, this Hagen sand wedge has a dramatically curved face and a large, broad sole.  Bobby Jones even used one of these in the 1930 British Open.  In 1931 the USGA adopted a new regulation that made any club with a concave face non-conforming.  Consequently, Hagen stopped producing its concave sand wedge.

This example appears unused—just a few light surface scratches on the face.  The original shaft still has most of its original decal. Hagen concave sand wedges can be found, but very few will be nicer than this one.