Opening/closing damper prevents outside elements from entering the vent. Damper is spring loaded to keep damper closed when not in use. For 3-1/4″ x 10″ duct. Damper spring controlled. Aluminum. Mill finish.
Semi-rigid aluminum duct is ideal when all aluminum duct is required by code in some gas and electric dryer applications. Totally noncombustible with a maximum operation temperature of 435 degree F.