Features Providing Make-Up Air For Exhaust Devices Is Easy, Controlling It Is Not - Until Now. Best® Directwire Make-Up Air Dampers, When Interlocked With Slave Dampers, Open In Unison To Provide Synchronized Operation For Kitchen, Bath And Whole House Ventilation Products. The Md10T Is Wired To The Transformer, Using Low Voltage Wiring, Which Signals The Damper To Open And Close While The Range Hood Is In Operation. The Intelligent Design Options Ensure Optimum Performance In A Variety Of Installations And Applications. (Ul)(Li)Interlocked Make-Up Air Dampers Provide Make-Up Air When Called For To Keep The Home Comfortable By Allowing The Range Hood To Operate At Optimum Levels(/Li)(Li)Directwire Design Works With Select Best® Range Hoods To Balance Indoor Air Pressure By Providing Interlocked Make-Up Air; Damper Opens Automatically When Fans Are Activated(/Li)(Li)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(/Li)(Li)Interlocked Make-Up Air Damper Systems Meet Irc Code Requirements For Make-Up Air With Range Hoods Over 400 Cfm(/Li)(Li)Interlocked 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 Environment(/Li)(Li)Fresh Air Wall Caps Are Required For Use With Make-Up Air Dampers(/Li)(/Ul)