DNA Air filter for Husqvarna Norden 901DNA replacement air filters are designed to increase hp and acceleration while providing excellent filtration. These filters are washable and reusable and are custom designed to fit into your existing factory air box. Their drop in design means adding performance is simple. They offer bigger air flow, with almost 99% filtering efficiency. This filter features DNA's advanced FCd and it is specially developed for Adventure Expedition Touring, on & off