Our High-Efficiency Takeoff (H.E.T.O) is designed with a rectangular opening and an approximate 45° slope on the body. A flange is turned out on all four sides with each corner being filled. The flange also has pre-punched holes for easy installation. There is a closed cell neoprene gasket (3/4” X 1/4”) applied to the flange to assure a tight seal. High-Efficiency Takeoffs are fabricated from both 26 and 24 gauge galvanized steel. The fittings come with and without volume dampers. The adjustable dampers are assembled using a spring loaded retractable bearing and positive locking hardware. Test data is available; call factory for more information. (Performed by ETL Testing Laboratories.)