Kair Brown Round Vent 100mm - 4 inch with Fly Screen - Wall Grille Designed for External or Internal Use Fits inside 100mm Round Pipe Part: DUCVKC250 or 102mm flexible hose part: DUCP0092/102/35. Flyscreen will help prevent insects entering the property via your duct run. Can be used as a stand-alone passive vent for cupboard doors or similar, or as a termination or supply point with your Bathroom or Kitchen extractor fan, 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, positive input, air conditioning, HVAC, and Heat Recovery Systems. For permanent fixings, seal joints with silicone sealant or tape. Easy to install clip in design Max / Min Temperature: +60c / -15c. Made in UK Polystyrene/Polypropylene plastic material Suitable to use in compliance with Part F Building Regulations Airflow performance independently tested by BSRIA or BRE. Free Air = 4,007 mm2 Static Pressure Drop in Pascals: 15 l/s = 22.50 Pa - 30 l/s = 75.80 Pa - 60 l/s = 291.90 Pa.