BROAN® 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 levels Universal 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 operating Slave 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 air Interlocked make-up air damper systems meet IRC Code requirements for make-up air with range hoods over 400 CFM Interlocked make-up air systems avoid wasted energy associated with barometr