-Will fit: Singer 15-86, 15-87, 15-88, 15-90, 15-91, 201, 201-2, 66, 99, 301, 401, 403, 404, 500, 503 and many more models.

-Medium size most common.

-Dimensions are: 1" 1/8 outside diameter, and 5/8" inside diameter.