Gammill bobbin winder O-Ring. This fits models where the bobbin lever pushes DOWN to engage. This only fits the all-metal winder that is built into the Gammill machine.
For a very small number of machines, your winder has a black plastic body and a chrome face and chrome colored screws. Inside, it uses a much smaller o-ring. This Large ring will be too large for your needs! Search for the 00-0207 instead.