This Kair Gravity Grille is a 150mm / 6 inch air exhaust outlet with a round spigot and non-return shutter flaps. These flaps automatically close when not in use to prevent unpleasant odours, noises, or draughts from flowing back into your property. The 6 inch / 150mm round male spigot on the back fits inside most comparable size pipes or hoses. It's easy to install with a simple push-fit connection. This grille is perfectly suited for use with extractor fans in bathrooms, toilets, or kitchens, as well as hydroponics in-line extract fans or cooker hoods. It can be used as part of a long ductwork run for various purposes including whole house ventilation, passive stack ventilation, positive input ventilation, air conditioning, HVAC, and Heat Recovery systems. Made in the UK, Kair products are compatible with a wide range of fittings and outlets for complete ventilation solutions. The external dimension is 183mm x 183mm, suitable for indoor or outdoor use. It complies with Part F Building Regulations and its airflow performance is independently tested.