The Johnson Controls A19ABA-40 is a remote bulb temperature control switch designed to regulate heating and cooling equipment based on temperature variations. It features a single-stage operation and a 6-degree Fahrenheit differential. This means the switch will turn on your heating system when the temperature falls 6 degrees below the set point and turn it off when the temperature ri... https://www.partshnc.com/30100-spst-close-on-rise-6ft