Limit Thermostat- 1/2" disc diameter - 300F Automatic Rollout, Normally Closed - Open On Rise - Cut out at 300F.  Automatically resets. For use on furnaces, dryers, fans, dishwashers, limits, ect., U.L.Rated, #SLS300. These limit thermostats are brand new and made by Supco/Napco Corp.