Designed to terminate your extract duct to an external wall. Louvered blades to reduce the effects of wind and Rain. Insect mesh Included. Easy to install, just push-fit duct and fittings together. Uv protected to prevent discoloring. Perfectly suited bathroom or kitchen extractor fan vent, hydroponics fan, or in-line extract fan. This grille can be used as a part of a long ductwork run for a variety of purposes including whole house ventilation, passive ventilation, air conditioning, HVAC, and Heat Recovery Systems. Suitable to use in compliance with Part F Building Regulations.