Not a rule I have seen before. Very practical and easy to read. Made by WOODMARK INDUSTRIES INC MINNEAPOLIS MINN.
Found online at https://slphistory.org/hwy74601/ :
WOODMARK INDUSTRIES
Woodmark Industries was incorporated March 29, 1946, at this address.
Woodmark produced a folding carpenter’s rule. A folding aluminum rule reportedly was introduced by Woodmark in the 1940s or 1950s, and is thought to be innovative because of the aluminum material and was considered competitive with folding rules manufactured by the large national Stanley tool company.