Universal design works with any BEST® 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 or MD8S) 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 | Fresh air wall caps are required for use with Make-Up Air Dampers