It's a 'Klixon' item, made in the USA by the the Spencer Thermostat Co. of Attleboro, Massachusetts. It appears to be a resettable thermal cut-out switch.
Stamped on the back are "T6A" and "C6373-7", but there's nothing that explicitly states the cut-out temperature.
This can go in my shoebox full of spare switches.
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Update -- FRIDAY, JUNE 5, 2015
The item has been sold.
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