Yesterday's Find

[Wrenchmensch]

A Diamond Calk Horseshoe Company calk wrench, 9 3/4" in length, with much of its original black paint still remaining, was found at a flea market yesterday.  I guesstimate this
wrench could be 45 years old or older since the word "Minnesota" is abbreviated as "MINN" in the front side's boss. Stylized outlines of a farrier's anvil surround both sides of the wrench's openings.     

The calk sizes, looking at the front of the wrench, are designated as "1 - 2" and "7  - 16" on the left end, and "5 - 8" and "9 - 16" on the right end.  (No forward slashes, as in "1/2", available in Duluth that day?)