Just a brief history on the, National brand made by Wagner. Explanation comes from a common collector website of cast iron to give them the credit.
Made 1914 to 1940. Likely chosen as a generic, patriotic name. Different designs vary in trademark placement or add the Wagner stylized logo, but all were of outside heat ring design. Online sellers occasionally erroneously claim the National brand was a predecessor of Wagner, perhaps the result of confusion with an unrelated brand of steel skillets seen marked National.
To talk about the skillet its lightweight and feels high quality, cooking surface is around 8.5 inches has typical light useage marks overall good to very good condition. I see no damages cracks and has been cleaned via electrolysis and is ready to season with the oil of your choice. Wagner is just as quality as Griswold and oftentimes less expensive.