With out any documenation I would guess the machine was made in the 1920s or 30s. The decals are simplified, black and gold only, but still elaborate enough to be prewar. From the Sewalot site I see elaborate decals were made up until the start of WWII. It has a smaller hand wheel than the very old machines, but still hard to know when German hand cranks went slimmer. I know from own experience it's easy to simiplify historical lines and develpments, and I know various models and technology went along side by side. If you read books you will come across terms like the "treadle era", and you will see round bobbin machines regarded as more modern than long bobbin, but actually round bobbin machines were common in the last decades of the 19. century, and long bobbin machines where made up until the 1960s (at least model 128). Some describe the threadle era as over by the 20s, but it looks like Singer and Bernina made treadle cabinets all through the 50s, but I'm not sure when the last one was made. On the web I have seen long bobbin swing arm zigzaggers (!). Lines of development aren't as one tracked or straight forward as we might be lead to think. I would not assume transverse shuttle models with the narrow slide plates went out of production with WWI, even though they gradually became fewer and fewer. In those days the were many more brands and makers than later, like today they merged, brand names were bought up, or went out of production. It's hard to give an accurate picture of the past. WWII were such a big break in many ways, it ruined a lot for many; including sewing machine production.