Bulk pack of clear plastic Class 66 bobbins with the classic curved sides used on many top-drop-in systems. Ideal for classrooms, repair benches and avid sewists who maintain multiple thread colours. Compatible with some Brother, Baby Lock and Singer machines; not for Pfaff, Janome, Elna, Bernina or Husqvarna models. Transparent bodies make thread levels easy to see and help keep your bobbin drawer organized during busy sewing sessions.