Features: High Quality: Using high-quality raw materials and advanced nanotechnology, it brings you fresh and healthy wind and supports the health of your family. EASY TO INSTALL: This replacement filter element is specially designed for USB air coolers without any special tools, it only takes about 2 minutes to complete, giving you a cool new air cooler. SAVE TIME & MONEY: Don't worry about your air cooler not working, just replace one filter element and you can use it again. Function: It can effectively block impurities, dust, etc. in the air, keep the air cooler clean. Absorption is fast and efficient. Frequency of replacement: It is recommended that the filter be replaced every 2-3 months to avoid excessive bacterial growth. Specifications: Material: Plastic + Non-woven Fabric Quantity: 28Pcs Filter Size: 12x11x12cm/4.72x4.72x4.33inch Package Includes: 28Pcs Filter Note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.