K&N 20-21 Freightliner Sprinter 3500 2.1L L4 Diesel Cabin Air FilterK&N Heavy Duty Cabin Air Filters replace your rig's stock cabin filter with a durable and reusable design that cleans and freshens incoming air. These robust cabin air filters help capture most mold, mildew, fungus, spores, bacteria, and germs controlling odors and contaminants inside the cabin during those long hauls. They are electrostatically charged to grab and hold dust particles. When they get dirty no need to replace, K&N's cabin air filters