The Southwark Metal ATHEWD6 is a 6" high-efficiency takeoff that includes a damper. It is designed with a rectangular opening, which can be connected to a flat duct or plenum to transition to a 6" round duct. This galvanized high-efficiency takeoff has a low-leakage damper hardware that improves ventilation. Please see the specification sheet for dimension details. This high-efficiency takeoff is just one of the many products that you can purchase from PlumbersStock.com, which is the perfect place to shop when looking to complete any residential or commercial project.