While I was home Sis and I were throwing away a bunch of old magazines and catalogs, and I came across this interesting piece. It's from the 1975 Spring and Summer Edition of a Montgomery Ward's Catalog. Guessin' it's BSR
Right you are Sam, the 5/8 fractions and the tab lid handles are BSR indicators.
While I don't remember their vendors, I do recall going to "Monkey Wards " with my parents. Entering the main doors, proceed down the asile a ways, as you turned left at the first cross asile, that is where the cast iron was displayed.