To determine your bobbin’s tension, place your bobbin inside the bobbin case with the thread unwinding in the correct direction, then feed it into the TOWA Tension Gauge. Take your bobbin thread and run it underneath the bottom wheel, over the top of the top wheel, and inside the catch. Pulling the thread to the side will show the top wheel moving down while the numbers increase. The higher the number, the tighter the tension. To release tension, turn the bobbin case screw counter-clockwise in small increments. The Towa Bobbin Case Tension Gauges are available for Class 15, L Stlye, o M Style bobbins.