Linear fans are installed in ventilation ducts for air exchange in rooms with low levels of contamination; they can operate in both supply and exhaust modes in either a vertical or horizontal orientation (VTR, WKA, WKO, WKW, WK, WP series). Depending on the type, they are made of ABS plastic or galvanized sheet metal. WP series units can be used as centrifugal fans to ventilate several rooms simultaneously. Thanks to the use of 3-speed motors (WP, WD series), it is possible to adjust the fan’s parameters to the user’s needs, depending on the connection method. This category includes units designed for installation in ducts with diameters of ø100, ø125, ø150, ø160, ø200, ø250, and ø315 mm. WD series roof fans are designed for vertical operation and installation on roofs with a maximum slope of 15°. Depending on the type, linear fans meet IP44 protection, which means protection against the ingress of foreign solid objects with a diameter exceeding 1.0 mm and against water jets from any direction, or IPX4, which allows for uninterrupted operation when exposed to water splashes from various directions at a rate of up to 10 liters per minute.