4" 100mm, 5" 125mm, 6" 150mm in line Extractor Fan Vent Back Draught Shutter (6" 150mm)

Please note that 4" 100mm shutters have 1 spring and not 2. This is correct as 2 springs would offer too much resistance Fit the shutter with the centre spindle of the flaps in a vertical position and make sure ducting is level, Manufacturer: fans4less