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.
Constructed of 4-ply aluminum foil laminate. Flexible. Ideal for gas and electric clothes dryer installations. Fire-resistant, will not support combustion. UL 2158A listed and marked.