The set includes 3 high-quality filters: F7 for the supply air and 2xG4 for exhaust air filtering. ISO16890 classification: F7: ePM1 70%, G4: Coarse 65%. Class F7 filters filter fine particles such as solid smog particles and thus ensure a high quality of indoor air even in heavily polluted areas. The pressure drop in class F7 filters is higher than for M5 or G4 filters, which is why they need to be changed more frequently and energy consumption may be higher. This filter set is best suited for areas with heavy air pollution: traffic-intensive zones, city centres, industrial areas and neighborhoods with solid fuel heaters.