Bosch Activated Charcoal Workshop Cabin Air Filters are designed to absorb foul smells in addition to capturing dust particles and harmful elements. This results in a noticeable improvement in the air quality inside the vehicle. Bosch Activated Charcoal Filters go one step further than particulate filters. Bosch Activated Charcoal Cabin Air Filters have a 5-layer design that includes an additional carbon layer that absorbs toxic and foul-smelling gases such as ozone, nitrogen oxide, sulfur dioxide and hydrocarbons, and an additional cover layer for extra protection. Bosch Activated Charcoal Workshop Cabin Air Filters feature high pleat counts that provide greater surface area for higher filtration capacity. Foam perimeter gasket (select part numbers where specified by OE) prevents harmful particles from bypassing the filter media. Rigid frame (select part numbers where specified by OE) adds stability for peak performance and long service life.