I found these near Troy NY, with the seller describing them as from General Electric, which I'm sure is right. I loved finding them as a group, representing a whole spectrum of jobs and roles (and individuals who filled them), from rigger to welder to machinist, and helper machinist, too--together a portrait of labor and expertise (and a sense of pride too I think) within a vast and iconic American corporation that built things. Of course I also like titles as words and phrases as they stand alone now--I would like to be a Helper General! And it feels very apt that "Brakeman" should be the most battered of the lot. 

1 11/16 d; smaller 1 1/2”. Ten buttons total, sold as a lot, exactly as pictured. Overall great condition. Some toning and surface cracking to Brakeman, as evident, and loss of the catch on back of Machinist, which would clasp the pinback. C. mid 20th century.