The BMW Cabin Air Filter is the one responsible for cleaning the incoming air for the HVAC system of your 2003 BMW 5401. It is very essential which provides a major purpose in your 5401 BMW. Cabin air filters were first introduced for European cars and has later become popular with the Asian models and makes. The main purpose of your BMW 5401 Cabin Filter is to trap bacteria, exhaust gases, pollens and dusts that have unintentionally in infiltrated the ventilation system of the vehicle. These are contamination elements that are considered aliens and provide no purpose to the system which is why they are filtered. Bacteria, as we all know and pollens can cause human allergic reaction that is why installing the top rated ACM Cabin Filter is a wise idea. This product is designed to provide optimum air filtering capability thus, ensuring you with air as clean and filtered as possible! Breathe clean air; shield your interior from harmful elements with BMW ACM Cabin Filter. Let ACM provide you with a clean and soothing air to sniff! This product is now available online. You can purchase this product at our site. Rest assured that we purchase defect free products and original by name and quality.