• Square or rectangular ceiling radiation butterfly damper • Designed for protection of ceiling openings in fire rated floor/ceiling assemblies with fire resistance ratings of 3 hours or less • UL listed and tested in accordance with UL Standard 555C • 3 hour fire resistance rating • Building materials rated 3 hours or less • CSFM California State Fire Marshal listed • Zinc plated steel closure spring • All steel parts with galvanized finish or zinc coating • 22 gauge butterfly style galvanized steel blades • 22 gauge galvanized steel roll formed frame • Ceramic fiber blade installation with fiberglass cover (Note: Ceramic fiber blade insulation is not UL required on dampers with free areas less than 80 square inches. Dampers above 80 square inches free area will be provided with blade insulation. • 165° replaceable fusible link