Limit Thermostat Switch - 230F Normally Closed, Open On Rise - 230F and below the electrical circuit will remain closed, 230F and up will open the electrical circuit. Automatic Reset - 3/4" Diameter.  For use on furnaces, air handlers, dryers, fans, dishwashers, package units, heaters, limits, ect. - U.L.Rated - #L230. These limit thermostat switches are brand new and made by Supco Corp.