This item replaces the Rollsizer wire lever. The spring action allows the lever to absorb the torsion created by the toolhead bolts. This is especially important if no cases are in the rollsizer track, a condition that normally begins to bend the original straight lever.
Testing has shown these springs to last in excess of 50,000 cases before they fail. The failure mode is the wire being worn away by the toolhead bolts.
They may require slight tuning for your particular setup. Place one leg in a vice and bend the other leg in the necessary direction. Do not repeatedly work a leg back and forth or you may cause premature failure in the part.
Two springs come in the package.