Cabin filters a.k.a. a pollen filter, dust filter, carbon filter or micro cabin filter is usually offer offered in one of two configurations to provide superior performance with a precise fit: 1. A particle cabin filter (single-stage) which is does not contain carbon and although it will filter dust particles, it is not as effective as a carbon filter for eliminating outside odors from entering the cabin. 2. A combination carbon filter (with additional carbon layer to remove odor), as mentioned is designed to stop dust particles, pollen and odors from entering the cabin of the motor vehicle.. When replaced on a recommended interval of every 12,000 miles, the filter protects passengers by eliminating nearly 100% of exhaust pollutants and airborne contaminants, and enables peak operating efficiency of the vehicle's HVAC system. Failure to replace the cabin filter at the recommended intervals can result in not only dust particle and odors entering the cabin, but a blocked up cabin filter will restrict the flow of air to enter the blower motor compartment and cause the blower motor and blower motor regulator to overheat and malfunction. Changing your cabin filters regularly can prevent this happening and you can avoid a huge expense of having to replace your blower motor and/or you blower motor regulator.