the pre-filters, placed in the intake ports, retain the macro impurities of the air, protecting the absolute filters behind them and thus prolonging their life.
ATTENTION. Given the high retention capacity of polluting agents dangerous for health, such as
pollens, spores and microorganisms (bacteria and viruses), when replacing the filters it is recommended
to use appropriate individual protective equipment (mask, gloves, glasses) designed to prevent
inhalation and, more generally, direct contact.