A low cost retrofit zone damper makes it easy for you to quickly add zone control to an existing home. No more having to remove a section of duct to install a round zone damper. A Retro Damper allows you to cut a slot in the duct and slide it in. The Retro Damper uses 18 gauge thermostat wire and will work with almost any zone control panel. The Retro Damper is a powered open powered closed damper and come in the following sizes: 5”, 6” 7” 8”, 9”, and 10”.