This Kair Gravity Grille is designed for efficient air ventilation, featuring a 150mm / 6-inch round rear spigot that fits most comparable size pipes and hoses. It includes non-return shutter flaps that automatically close when not in use, preventing unpleasant odours, noises, or draughts from flowing back into your property. The grille is made of durable white plastic and is easy to install with a simple push-fit system. It's perfectly suited for various applications, including bathroom and kitchen extractor fans, hydroponics, and in-line extract fans. This product can be integrated into longer ductwork runs for purposes such as whole house ventilation, passive ventilation, air conditioning, HVAC, and Heat Recovery systems. It complies with Part F Building Regulations, and its airflow performance has been independently tested. The external dimensions are 183mm x 183mm, suitable for both indoor and outdoor use. Kair products are manufactured in the UK and are compatible with a wide range of Kair ventilation components.