Gas filter device i.e. air filter, for filtering gaseous medium of cylinder in internal combustion engine, has prefilter element extended along flowing against side of U-shaped main filter element

The device (1) has a prefilter element (10) extended along a flowing against side of a U-shaped main filter element (2). The prefilter element is adjacent to forehead edges of the main filter element that comprises a rectilinear portion at the flowing against side. The prefilter element is immediately applied or glued on the flowing against side of the main filter element, where the prefilter element includes hydrophobic properties. A radial outer side of the main filter element forms the flowing against side. The main filter element is arranged between two cover disks (5, 6). The U-shaped main filter element is designed as a folding filter. The prefilter element is designed as a web of interwoven fibers. Eine Gas-Filtereinrichtung weist ein Hauptfilterelement auf, das eine nicht-geschlossene, abschnittsweise gekrümmte Anströmseite besitzt. Des Weiteren ist ein Vorfilterelement vorgesehen, das sich entlang der gekrümmten Anströmseite des Hauptfilterelementes erstreckt.