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 BROAN 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.FeaturesBROAN® interlocked make-up air dampers provide outside air when required to keep the air in the home fresher by allowing the range hood to operate at optimum levelsUniversal design works with any BROAN® range hood to balance indoor air pressure by providing interlocked make-up air without requiring a direct wire connection between the range hood and the damper. Instead a sensor is attached to the exhaust duct to detect if the range hood is operatingSlave dampers (MD6S- MD8S or MD10S) are interlocked to the main automatic or universal make-up air damper and open in unison for synchronized operation. They close- along with the main damper- as soon as the range hood is powered off. Slave dampers can be “ganged” together to provide a cost effective means to provide for higher volumes of make-up airInterlocked make-up air damper systems meet IRC Code requirements for make-up air with range hoods over 400 CFMInterlocked make-up air systems avoid wasted energy associated with barometric solutions and do not let unwanted air into the home during heating or cooling activities so air pressure is equalized for a well-balanced environmentFresh air wall caps are required for use with Make-Up Air DampersSize - 6 in.