It's not entirely clear to me what this item is for. I think it may be for starting motors that don't employ an integral centrifugal switch for energizing/de-energizing the start winding.
This appears to be an item that's been long out of production. I think that Cutler-Hammer was acquired by Eaton at some point, but I can't seem to find the story of that.
In any event, I have sixteen of these. I'll stash them in my miscellaneous switches bin.
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