Singer Zig Zag Bobbin Case Genuine

The bobbin case is the part of the sewing machine that the bobbin is inserted into, that holds the tension of the bobbin thread. Tension is adjustable via a screw on the side of the bobbin case. Be sure to use the bobbins that are specifically designed to work with this bobbin case, as other bobbins will cause skipped stitches and can cause bigger problems for your sewing machine.