Formaldehyde Removal: The Mi Air Purifier Formaldehyde Filter S1 is specifically designed to remove formaldehyde from the air High-Efficiency Filtration : The filter features a three-layer composite design that combines a pre-filter. Long Lifespan: The filter has a long lifespan of up to 6 months, depending on the air quality and usage patterns. Easy Installation: The filter can be easily installed in the Mi Air Purifier, with no special tools or skills required. Compatible with Mi Home App: The Mi Air Purifier Formaldehyde Filter S1 is compatible with the Mi Home app.