Backdraft damper with galvanized steel collar and lightweight aluminum damper blades. Spring loaded for positive closure.  Fits 4" Round Duct

. 20 gauge galvanized steel housing
. Aluminum spring loaded butterfly damper blades
. Damper seals against EDPM rubber gasket in closed position for minimal leakage
. Gasket designed for use in temperatures from - 22°F  to 180°F
. Require from 0.04 to 0.08 inches W.G. to begin to open
. May be installed in any position.
. Simple installation - entire assembly inserts into duct
. Exterior foam gaskets assure a tight seal against interior surface of duct