SUPERDYMA SHEET: The external cover of the outdoor unit is made up of Superdyma metal sheet which is highly rust resistant. This makes the outdoor unit rust free and eliminates the need for painting or any other kind of maintenance.PM2.5 Filter: PM2.5 gives you dust free clean air. It removes up to 85% of PM2.5 in the air. CATECHIN FILTER: Catechin Filter deactivates 90% of bacteria trapped.2 Stage Air PurificationFire Retardant