DENSO First Time Fit replacement Cabin Air Filter are engineered for optimal airflow and filtration meeting all OE requirements to the letter. Up to five layers of filter media are used to trap impurities down to just 0.001 micron in size. Just as with engine air filters some discount suppliers are known to cut corners on quality to save a few cents. A cut-rate price may turn out to be no bargain. What consumers really want is value and DENSO First Time Fit cabin air filters deliver it.