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 shows minor use and is in excellent condition over all. The shaft and grip are original.

For more on Edwin McClain's scooped out sand wedge, see TCA2 Vol. 1 p. 283-284