Spalding waterfall backspin irons were produced primarily in 1920 and 1921 under a patent issued in 1919 to William F. Reach. They were designed to add backspin to the golfers shots, be it a traditional strike or a cut sot.
This example is stamped "Spalding Kro-Flite" etc. On the back of the blade along with “A. G. Spalding & Bros.” in script. It is also marked "Pat Applied For," so you know it's an earlier model. Nice original shaft that has been regripped with a period grip.