Item Type: Air Purifier Filter Material: High Efficiency Particulate Air, cotton and activated carbon Color: Green Applicable Models: For Xiaomi 1 ,2 ,3 ,4, 2S, PRO (not suitable for Xiaomi 4 lite) Package List 1 x Filter Outer Ring 1 x Filter Inner Ring 1. It is recommended to replace the filter every 3 tp 6 months, or depending on the use 2. This product is not suitable for Xiaomi 4 lite 1ACTIVATED CHARCOAL LAYER: The activated carbon used in the filter is one of the most effective of its kind, combined with an anti formaldehyde formula that effectively absorbs harmful chemicals. 2OPTIMAL STANDARD: The filtered air from this cartridge ensures a clean room climate and high air quality that meets the high efficiency particulate air standard. 3EFFECTIVE FILTERING: The cartridge has a triple filtration system that filters 99.9% of dust, pollen, pet hair, etc. to ensure air quality. 4APPLICABLE MODEL: For Xiaomi Air Purifier 1, for Xiaomi Air Purifier 2, for Xiaomi Air Purifier 2S, for Xiaomi Air Purifier 2H, for Xiaomi Air Purifier 3, for Xiaomi Air Purifier 3H, for Xiaomi Air Purifier Pro, for Xiaomi Air Purifier MAX. 5PERFECT REPLACEMENT: This is a great replacement filter, and the clean air delivery rate after replacement is comparable to the original.