This 4-inch/100mm plastic ducting air inlet/outlet features gravity shutters and a round male spigot on the back, making it versatile for both indoor and outdoor use. Designed to terminate your extract duct to an external wall, it includes non-return shutter flaps that close automatically when not in use, preventing unpleasant odours, noises, or draughts from flowing back through your duct. The gravity-operated flaps, designed without the need for springs, ensure reliability and longevity. Installation is straightforward with a push-fit system for ducts and fittings, making it ideal for bathroom or kitchen extractor fans, hydroponics fans, or in-line extract fans. Additionally, this grille supports a variety of ventilation purposes, including whole house ventilation, passive ventilation, positive input, air conditioning, HVAC, and heat recovery systems, and complies with part F building regulations.