The Brink FLAIR 325/400 MERV13 (F7) high quality filter removes >90% of fine particulate matter from the outside air before the HRV/ERV core and before the air is supplied to your home for excellent, healthy, indoor air quality. The MERV13 filter should be changed at a minimum interval of 6 months to guarantee optimal functioning of the ventilation system. Changing the filter more frequently may be necessary in areas with poor air quality or during smoke events.