You definitely have an older Featherweight but Singer never changed the bobbins in any of the Featherweight variations. Black ones, tan ones and the white ones all need the same narrow bobbin. Your local sewing machine store may carry Featherweight bobbins even if they sell other brands as many people have a Featherweight and want more bobbins. I think new machines were only sold with five bobbins (that's what my MIL got with her new machine purchased in 1950). There's lots of information on the web if you google Featherweight.