Knut Bø MURO 100 BK is a 4-inch (Ø100) bathroom extract fan with an integrated non-return damper and a single-pole pull-cord switch for local on/off control. Free-air delivery is 90 m³/h. Typical use is direct extraction from a bathroom, WC or small utility room through a Ø100 mm duct to atmosphere. Made in Italy.