The Xiaomi Mi Air Purifier Filter SCG4013HK is a new filter set for your Xiaomi Mi Air Purifier 2S. In this set you will find a pre-filter, HEPA filter and carbon filter. The filters are together in one cylinder. Handy, because you can place them in the air cleaner in one go. For optimum cleaning you have to replace the filters every 3 to 6 months.