K&N Engineering is the creator and top supplier of reusable cotton gauze filter technology for car applications. Currently, K&N exists as the sales and brand leader for auto performance filters with more than 3,500 part numbers, with a wide-ranging line of factory replacement drop-in filters, FIPK (Fuel Injection Performance Kit) applications, and its stock of innovative car Performance Gold oil filters. K&N's air filter is made with cotton gauze material, inserted between mesh made of aluminum wire. The K and N filter is designed to be occasionally cleaned and recoated with oil. K&N Engineering offers a million-mile automotive warranty and says its air filters are friendly for the environment than normal air filters, since they never need to be changed or discarded to landfills or incinerators. Other K&N products include air filters, cold air intake system kits, performance fuel injection kits, and oil filters.