Broan 10" universal make-up air damper. Designed to provide the best technology to equalize pressure between indoors and outdoors, while providing effective ventilation for a cleaner, healthier home. Eliminate gases, smoke or particulates generated from naturally vented combustion devices like a fireplace or water heater. Only BEST offers such a complete and simple solution for automatic and controlled fresh air into the home every time you turn on the range hood! This is an interlocked, synchronized system that installs easily and requires only low voltage wiring to the sensor. Perfect for new construction or retrofit into an existing home.