Dayton fire/smoke dampers are designed for use in HVAC system applications where emergency fire/smoke control is required. Each damper comes standard with a 165ºF electro thermal link and factory installed actuator. Upon temperature elevation in emergency fire smoke situations, dynamic damper closes automatically to prevent the spread of fire and smoke. Factory installed actuators are wired to a single junction box to provide easy, single point wiring installation. Qualified to UL Standard 555 as a 11/2 hour fire damper and UL Standard 555S leakage class of II.