K&N: Washable Lifetime Performance Air Filter (Expedition 15+)
K&N's washable lifetime performance air filters are designed to increase horsepower and acceleration, while providing excellent filtration. K&N makes over 1,200 different replacement air filters for virtually every vehicle on the road. These filters are washable and reusable and are custom-designed to fit into your existing factory air box. Their drop-in design means that adding performance is simple. With most vehicles, you simply remove the disposable air filter and replace it with one of these K&N air filters.