This new rubber bobbin winder tire is for most Singer Sewing Machines (just not the Singer Featherweight 221 or 222). If your rubber bobbin winder wheel is old, grey and brittle, then it most likely needs to be replaced for a better grip - making bobbin winding that much easier.
Fits most vintage Singer Models: 15, 66, 99, 192 Spartan, 201, 301, 401, 403, 404, 500, 503, and many more models, etc.