Priced and sold per 5 pack of bobbins. B9 Hook Bobbins hold 70% more thread than standard bobbins. This enables you to sew for even longer without interruption. B9 Hook Bobbins and Bobbin Cases are required for the following BERNINA 7 Series machines: B 710, B 750 QE and B 780. Also compatible for BERNINA Series 4 and Series 5 machines.