(Optimal Size) Compact and easy to use bobbin winder automatically stops when bobbin is fully wound. (Versatile) Works with plastic and metal bobbins, extra spindle for bobbin of PFAFF/VIKING machine. (Efficient) Wind bobbins quickly without using a sewing machine. (Universal) Hemline's automatic bobbin winder is designed for a wide range of normal and large size spools. (Electronic) Operated by 3 x AA batteries (not included) or common USB Type-C cable and adapter (not included).