Draft Blocker – 4″

Keep unwanted outdoor air where it belongs with the Deflecto 4-Inch Dryer Vent Draft Blocker BD04. With its 4‑inch diameter opening, this draft blocker connects securely to standard 4-inch diameter dryer ducts, bathroom exhaust fans, and residential venting systems. Measuring 5” wide by 5” high with 2.5″depth, it installs inline between vent pipe and exterior hood, making it versatile for multiple applications. The heart of the design is a gravity‑balanced damper flap that responds instantly to airflow. When your dryer or exhaust fan is running, the flap opens to allow air to pass freely. Once the appliance is off, the flap closes automatically, creating a one‑way seal that limits drafts and keeps outdoor debris from entering your home through your vent. This simple maintenance-friendly design provides steady one-way airflow operation without complicated components. Constructed from durable calcium-filled polypropylene, this vent draft blocker is designed for dryer and bathroom exhaust applications and everyday residential use. The lightweight plastic construction makes it rust-resistant while standing up to heat commonly found in venting systems. Its compact profile also allows installation in areas with limited space. The unit arrives fully assembled and ready for installation. Compatible with a variety of installation methods for flexible and rigid duct systems, allowing you to choose the clamps, adhesive, or sealant appropriate for your vent configuration. Mounting screws are not included.