Broan-NuTone 110RDB Finish Pack. 110 CFM, 4.0 Sones. Blower with metal grille. To be used with Model RDA housing pack. • Many local codes require that exhaust fans installed in fire-rated ceilings must be protected by dampers, which, in case o f fire, protect against the spread of heat and flame • Being fire-rated means the ability of a wall, floor/ceiling, or roof/ceiling to withstand the effects of fire for a specified period of time. NuTone ceiling radiation dampers are designed to protect the openings in 1-, 2-, or 3-hour fire-rated floor-ceiling and roof-ceiling designs • When the temperature of the air passing through the damper exceeds 165°F, the fusible link melts and the thermal fabric across the damper closes a utomatically to interrupt the airflow by becoming a flame and heat barrier, preventing rapid spread of fire to other areas Broan-NuTone 110RDB Finish Pack. 110 CFM, 4.0 Sones. Blower with metal grille. To be used with Model RDA housing pack. Feature s: • Housings and finishes (motor assembly and grille) sold separately in units of four per carton - purchase housings for rough-in and blower assemblies/grilles later for finishing • UL classified (UL standard 555C) for use in 1-, 2-, or 3 -hour fire-rated floor-ceiling and roof-ceiling designs • Warnock Hersey Listing allows use in combustible ceilings with ducted fans • High temperature, non-asbestos, reinforced fiber thermal fabric • Galvanized steel frame • 165& deg;F fusible link • Stainless steel negator-type closure spring • Available from 50 CFM to 110 CFM • Radiation damper comes attached to housing • Blower assembly will fit into housing without the removal of the radiation damper - one less step in installation process • 110CFM BLOWER W/METAL GRILL