K And N's replacement air filters are designed to increase horsepower and acceleration while providing excellent filtration. K And N filters are custom designed to fit into your existing factory air box for simple, fast installation. K And N stock replacement air filters for street vehicles are covered by a Million-Mile Limited Warranty making this the only filter you will ever have to buy for your Mazdaspeed Protege. K And N Filters use oil to provide filtration, and can be washed and recharged using the K And N cleaning kit (sold separately).