Duct Backdraft Damper; Type Round, Spring Loaded; Duct Size 4 Inch Diameter; Material Thickness 24 Gauge; Blade Material H14 Aluminum; Inclusions/Features 3/32 Inch Diameter Brass Central Rod, EPBM Synthetic Rubber Gasket; Length 3-1/4 Inch; Case Material G90 Galvanized Steel