Small automatic reset 125F CLOSE ON RISE snap switch found in many Quadra Fire models often referred to as snap disc #1 or the room fan switch. Switch is normally open and closes when the temperature reaches approx. 122 degrees Fahrenheit (+/- 5 degrees) and resets when the temp drops to around 90F. Quad part no. cross reference is 812-1560 This is a CERAMIC case switch, not phenolic.