This is a High quality Bobbin Case for Singer FeatherWeight Sewing Machines.  221,221k,222k,301

Part #45751 BC-HR221

Please note the size of the bobbin case shown in the pictures,to see if this bobbin case can fit your rotary hook.

If your original bobbin case was marked 45750 as in some of the earlier Featherweights( came off an late 40's or early 1950's)
, then this bobbin case may not fit or if fits may hang the thread occassionally.