Knut Bø MURO 100 BK-12V is a 4-inch (100 mm) SELV bathroom extract fan operating from a 12 V safety extra-low voltage supply. It is fitted with a backdraft damper and a single-pole pull-cord switch for local operator control. The low-voltage supply suits installation in wet-zone locations where mains-voltage fans are not permitted. Typical applications are shower rooms, wet-room ceilings and marine cabins requiring code-compliant humidity extraction.