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.