4 Inch / 100 mm Draft Blocker Backdraft Damper Stopper Backflow Preventer Inline Fan Vent Deflector One Way Airflow Ducting Dryer Duct Connector with Backdraught Flap

DIMENSIONS – Fits Ø4 Inch (100mm) round ducts; Insertion diameter: 3.89 inch (99mm). Total width: 3.46 Inch (88mm). Precision-engineered for a tight internal fit inside metal ventilation pipes for reliable, airtight performance. AUTOMATIC BACKDRAFT CONTROL – 4 Inch inline draft stopper features spring-loaded flaps that open only in the outflow direction, stopping reverse airflow, cold air, odors, and unwanted drafts while keeping HVAC duct systems efficient and quiet. DURABLE GALVANIZED STEEL – Heavy-duty galvanized steel backflow damper with smooth spring action, prevents rattling and air leakage. Built to withstand high temperatures, moisture, and continuous use in dryer vents, kitchen exhausts, HVAC ductwork, and heating systems. EASY INSTALLATION – Simply insert the draft blocker into round ducting until the stop edge; fits Ø4 Inch metal ventilation pipes for a secure seal. INSTALLED ONLY HORIZONTALLY for optimal one-way airflow in your duct system. WIDE HVAC APPLICATIONS – Designed as a backdraft shutter for air conditioners, dryers, cooker hoods, bathroom exhausts, inline ventilation fans, range hoods, and heating ducts. Works with rigid or flexible metal ducting and spiral pipe connectors, ensuring efficient backflow prevention in residential and commercial ventilation.