Stylish stainless steel (grade 304) gravity flap vent outlet with 150mm (6") spigot. Complete with rubber seals and fixings. Minimum free area of 16,286mm2 Fitted with 4 anti-backdraft shutters which open during fan operation and close when the fan is switched off. The shutters are designed to prevent external airflow or wind pressure from entering the property. Perfect for intermittent extract fans, cooker hoods or tumble dryers.