Broan-NuTone Radiation Damper 11 5/8 by 10 3/4 for Ventilation Fans.

The BROAN RDFU Radiation Damper prevents the rapid spread of fire to other areas of a home during a fire. Many codes require that exhaust fans installed in multi-family homes, with fire-rated ceilings, must be protected by radiation dampers. When the air temperature passing through the damper exceeds 165F the fusible link melts, triggering the thermal fabric to automatically close across the damper. Airflow is interrupted by a flame and heat barrier, preventing the rapid spread of fire to other areas of the home.