Special accessory for recirculation operation suitable for glass slanted hoods. Odor reduction of over 90%. Lifespan of the Clean Air Plus odor filter is 12 to 18 months. Anti-fish function: Special impregnation against fish odor. Anti-pollen function: The filter retains 99% of airborne pollen and deactivates allergens trapped in the filter. Consists of 2 Clean Air Plus activated carbon filters, recirculation diverter, flexible hose, 2 hose clamps, and mounting materials. Please check if this recirculation set is compatible with your range hood. If you have any questions, we are happy to assist you.