Stanley 39 Dado Plane

I don't often look at old planes too much, this one caught my eye. Between the years 1902 and 1952, Stanley made the #39 plane in 7 sizes, 1/4, 3/8, 1/2, 5/8, 3/4, 13/16 and 7/8". They seem to be a sought after tool.

Datamp Patent 706,704