125mm (5") cowled outlet with gravity flap. Designed for installation on exposed external walls where wind or back pressure against the ventilation unit are present. The cowled outlet is designed to shield the duct from the wind and deflect the air away. The gravity (non-return) flap acts as an additional measure to prevent airflow returning through the duct. As the ventilation unit operates the flap lifts to allow the exhaust air to disperse into the atmosphere. DESIGNED FOR EXHAUST AIR ONLY.