170 mm x 170 mm Silver Matt Air Vent Grille for 100 mm Round Duct Hose Pipe Connection. Heavy Duty. Simple To Fit. Ducting Ventilation Cover Fly Net Wall Ceiling with Fly Screen / Anti-Insect Mesh. Used as vents to rooms on the outside and inside of the building (basements, garages, drying rooms and attics). Tough and Strong ABS Plastic. Easy, simple and secure to fit.