The finger points another direction as Cathy said but there is a slot in the bobbin case that can be long or short for the 15s. If you get the wrong one you will know - needles break when they hit metal.... I'm not exactly sure why some machines have the long slot but I'm thinking it has to do with whether or not the bobbin faces you or the side. If I were at my shop I would photograph the difference for you. I'm taking care of my Mom. She has not been doing well.