The AEM-21-785DS is designed to replace the restrictive air filter and airbox of some BMW 320i and 328i models with 2.0L turbo 4 cylinder engines. This enclosed system is designed with an upper and lower airbox to maximize air supply to the air filter, and acts as a heatshield. The cylinder shaped AEM Dryflow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions). A MAF sensor extension and other hardware is provided for the installation. An AEM logo provides the finishing touche on the airbox cover. Designed to increase horsepower this air intake system also gives the BMW's engine a facelift. The air intake system is backed by AEM's Lifetime Limited Warranty. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards, while others are 50 state legal. View the 21-785DS vehicle applications to determine the legal status for each vehicle. The AEM-21-785DS intake system has an enclosed air box design and consists of upper and lower air box, an over-sized AEM Dry Flow axial seal filter and all of the necessary hardware to install the intake.