9" x 3" - For openings upto 229mm x 76mm (FREE AIRSPACE 2240mm). 9" x 6" - For openings upto 229mm x 152mm (FREE AIRSPACE 4680mm). 9" x 9" - For openings upto 229mm x 229mm (FREE AIRSPACE 6350mm). Introducing the SISI UK Adjustable Air Vent Cover, perfect for any room in need of increased air flow.
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