The right Audi Air Filter & Cleaner in your German made vehicle can make a positive contribution to its performance as well the longevity of your vehicle. The reason to have one of these important parts in place at all times include not only to keep dust and debris out of your Audi engine but to also help in providing the right amount of air into the intake so the correct air to fuel ratio can be achieved. To help bring in perspective the size of the particles the air filter & cleaner keeps out of your engines intake system, the size of a human hair should been known. On average they are only 50 microns in thickness. The average air filter & cleaner is made to filter out particles as small as 5 microns. With this type of purification system on the air intake of your Audi engine, even the smallest parts will be protected from the damaging effects of dirt and debris that might try to enter. The material an Audi Air Filter & Cleaner is made from includes a paper element bonded together with a polymer to keep the element in the correct shape and the compartments of the element separated to ensure sufficient air flow can be maintained thru to the engine. The shape designed by the Audi engineers in generally was rectangular. The reason for the 137 different sizes of this auto part was to make it fits under the hood appropriately for each year and make of your car that was produced throughout the years. It is true that some air filter & cleaners can be cleaned by removing them and shaking out the trapped particles, but nothing will permit the air flow of a new one and replacing the old one. There is no way to remove the 5 micron and smaller debris elements from the air filter & cleaner known today.