This Tamarack Backdraft Damper uses a specially formulated fabric sleeve attached to an outer metal sleeve to allow maximum airflow while stopping cold air from entering your home. Features . Overcomes inefficiencies and limitations of other damper designs. Silent operation - no noisy clanging noises. Easy installation. Size - 4 in. diameter. Fuel Type - Exhaust fans. Product Style - Backdraft damper. Material Type - Fabric. Dimension - 1 x 4 x 6 in.. Item Weight - 4 lbs.