Best Range Hoods MD6TU 6" Universal Make Up Air Damper fridge_height_63 All Blowers Purchased Separately Variable Speed All Blowers Purchased Separately Variable Speed Electronic Controls Offer A Range Of Ventilation Speeds To Remove Smoke And Grease For The Most Affective Operation Heat Sentry™ Detects Excessive Heat And Adjusts Blower Speed To High Automatically To Prolong Product Life Dual Level Halogen Bulbs (Mr16 Field reversible door Synchronized System That Installs Easily And Requires Only Low Voltage Wiring To The Sensor (Ul)(Li)Best® 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( Li)(Li)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