Bobbin Case Tension Gauge Towa Tm-1 Style L Bobbin Case Japan Towa Bobbin Case Tension Gauge TM-1 For "L" Size Bobbins. For use with Style L bobbins. The Towa bobbin tension gauge allows you to consistently set accurate bobbin tensions. With the Towa Bobbin Case Tension Gauge the guess work is gone forever. This gauge allows embroiderers to consistently set accurate embroidery bobbin case tension. In just a few seconds you can verify your bobbin tension is where it should be to achieve optimum results. It's simple to use and comes with complete instructions. No setup is required. Very simple to use with no installation. Comes with complete instructions in maximizing the benefit of this tool. Provides accurate and consistent tensions. Much more reliable than the outdated, and unreliable drop test. Made in Japan