The ENERGY STAR« Qualified Fire Rated Exhaust Fan provides 100 CFM of cost effective and energy efficient ventilation at 1.5 Sones. It is designed to automatically shut off and seal the duct from the rest of the dwelling once the temperature of the air passing through the damper exceeds that of the fusible link. It installs easily using the adjustable hanging brackets and the side access panel allows the fan to be wired without removing the interior components. It features a 4" metal duct collar with damper to protect against back drafts and ensure quiet operation. UL Listed for Wood Frame Construction truss designs: L501, L502, L503, L506, L507, L508, L512, L513, L514, L515, L516, L517, L519, L522, L523, L533, L537, L545, L581 and L583.