MicronAir Particle Cabin Air Filter, fits Mercedes-Benz CLK-Class (W203) 2003-2012 requires 1 filter, and C-Class (W203) 2001-2012 requires 1 filter. Traps Harmful pollutants before they reach your vehicle's interior and provides cleaner air for allergy and asthma sufferers. Vehicle manufacturer recommends filter be changed every 6 to 12 months.