The replacement filter is suitable for portable USB air purifiers, which can be absorbed quickly and effectively Function: It can effectively block impurities,, in the air, improve the, and keep the air cooler clean : No need but your air cooler does not work, you only need to replace a filter and you can use it again, allowing you to breathe for and wind and protect the for health of your family Replacement frequency: It is recommended that the filter be replaced every 2-3 months to avoid excessive use of product bacterium : This replacement filter is specially designed for second generation USB air coolers, without any special tools, it only takes about 2 minutes to complete, giving you a cool and cooler