Extension spring used on United and early Williams 50 step unit assemblies and others.
Reference:
- 10A-227 extension spring
- 10-227
- 10A-224
- 10A-242
- 10A-228 extension spring
- C-6510 non-resetting 50 step unit with bell
- C-6510A non-resetting 50 step unit without bell
- C-6494 resetting 50 step unit