Designed to replace the deep-groove backspin irons declared illegal by the R&A in 1921, Mac & Mac of Oak Park, Illinois, introduced their Deep Dimple Face irons in 1923. These new irons used large round holes cut into the face in order to create backspin and eliminate side spin, or so they advertised. Truth be told, if a golfer were to cut across the ball a little they'd get more sidespin than they bargained for....

This iron, made from Granger steel and so marked, is in outstanding original condition.  The back is well marked and the 37" shaft and grip are original. 

For more on the Deep Dimple Face iron, see TCA2 v1 p 277