I was going to ask if you had an idea of the "vintage" - but it looks like you know exactly that!
I've seen some sets that are in a fold up case with a snap, and then the ones in the molded box like you have. Was wondering what the age difference was - though maybe they were just made for different markets.
I've seen the same style box/buttonholer with the Domestic name molded in, but then White took over Domestic in the 20's, so that I guess that would be expected.