Bernina CB Bobbins - Single Bobbin Each BERNINA sewing machine has a special hook for bobbins and bobbin cases. Different bobbin cases are therefore available, depending on the machine. The CB Hook is used in particular for sewing utility and decorative stitches with a stitch width of up to 5.5 mm. Each BERNINA sewing machine has a special hook for bobbins and bobbin cases. Different bobbin cases are therefore available, depending on the machine. The CB Hook is used in particular for sewing utility and decorative stitches with a stitch width of up to 5.5 mm. This foot is compatible with machine type • A1 (910–933/1004–1031/1080–1530)