OEM air filter assembly from Stihl. This filter assembly includes an air filter, air filter housing and 2 attachment nuts. The filter has a fleece (flocked) material on the surface that picks up fine particles of dust. They filter very well (which is a good thing), but tend to ice up in sub freezing conditions. We recommend a nylon mesh filter for frozen sawing conditions. These filters can load up quickly, so keep a couple of spares handy. This filter system replaces the old style screw on air filter, which is no longer available.