1775L In-Line Draft Blocker, 4 in Hose Inside Dia, Plastic, White, In-Line Installation

The Lambro white plastic in-line draft blocker is ideal for preventing outside air from entering into the home. This accessory can be installed in-line with the duct to the outside vent for clothes dryer exhaust, bath fan exhaust and other general venting applications. When the exhaust airflow is not active, the draft blocker prevents outside air from entering back through the exhaust unit.