The 1900+ Waltham design to make a fashionable small thin p.w. using w.w. movements was not very successful for large quantity production but a good quality design that is interesting to me. They used a wide variety of their early first w.w. movements in pocketable small sizes; commonly 12 size. Successful enough so Gruen, Elgin, others copied the style. Have several of the better ones. A good 18k cased Riverside Waltham with its fancy box, 14k cased diamond Maximus; one of the rarest Maximus named movements. and a Gruen with their earliest w.w. movement also used by early Rolex w.w. Two photos of boxed one allowed by dealer.