Bobbin Boat™ by Dritz^® keeps your bobbins securely in place. The curved interior of the boat "hugs" the bobbins for a snug fit. Bobbin Boat holds 10 Class 15 (Style A) bobbins, which is the bobbin size compatible with Ultrafeed^®, Leatherwork^® and many home sewing machines. With its curved design, you can toss it in your sewing toolbox and the bobbins will stay in place.