These are all styles of the stitch length indicators for the black Featherweights. The chrome indicator was the standard issue on US Featherweights from 1933-1941. The all black or "blackside" stitch length indicator was produced during 1941 and 1945, and was put on just a select few Featherweights from those years. The most common black stitch length indicator with the silver outline came on all US Featherweights from 1946 to 1957. These original indicators will also come with original screws, (chrome screws for the chrome indicator and black screws for the black indicators.) We also offer original stitch length levers if yours happens to be bent or broken. If you have any questions feel free to contact us and we will be happy to help you.