Limit Thermostat Switch, 275F - Automatic Reset - Normally Closed, Open On Rise, 275F and below the electrical circuit will remain closed. Above 275F will open the electrical circuit. 3/4" Diameter. For use on furnaces, dryers, fans, dishwashers, package units, heaters, limits, ect., U.L.Rated, #L275. These limit thermostats are brand new and made by Napco Corp.