Bosch Activated Charcoal Workshop Cabin Air Filters feature a multi-layer media that offers a 99 percent efficiency rate at 3 microns or greater in keeping dirt and other particles from entering vehicle heating and air vents 1st Layer - Non-woven pre-filter layer captures larger particles 2nd Layer - Electrostatically charged microfiber layer attracts and holds elusive smaller particles 3rd & 4th Layers - Non-woven cover layers add stability to protect the microfiber layer from damage and act as an additional barrier to harmful elements 5th Layer - Activated charcoal layer absorbs toxic and foul-smelling gases such as ozone, nitrogen oxide, sulfur dioxide and hydrocarbons which results in fresher smelling air and reduced windshield hazing Compatible with select vehicles (Note: vehicle trim level may affect fitment - verify specific vehicle fitment details with fit checker above): ACURA: 2001-03 CL, 1999-03 TL; HONDA: 1998-02 Accord