VKC292BEIGE 150mm (6") gravity outlet to fit 150mm (6") round ducting 150mm Beige Gravity Flap Outlet manufactured from high impact polypropylene and has a minimum free area of 16,000mm² and has a 150mm male spigot for connection inside the duct. This outlet is supplied complete with 4 anti backdraft shutters which will open during fan operation and close when the fan is switched off. The shutters reduce external airflow or wind pressure from travelling through the ducting and into the property,