There were a lot of machines that used this hook. Domestic, White, and Kenmore were the most common. You can
still find them on Bonanza and Ebay. The hook it uses will be determined by the type of bobbin case it uses. Hopefully
you have the bobbin case to look at. There were two basic types of bobbin case that used these bobbins.
There are still quite a few rotating hook and bobbin case assemblies out there for sale off of old machines. If you
see an assembly using your bobbin case then you probably have the right one. There are still manuals around for
these old machines. A manual with pictures would also help identify the type.