125mm (5") gravity outlet to fit 125mm (5") round ducting 125mm White Gravity Flap Outlet manufactured from high impact polypropylene and has a minimum free area of 11,600mm² and has a 125mm male spigot for connection inside the duct. This outlet is supplied complete with 3 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, Measures 155mm x 155mm on outside edge. Perfect for cooker hoods, extraction systems and tumble dryers.