The use of electrostatic filter material, can effectively isolate the air 0.2m particulate pollutants, the dust filter efficiency of 0.5m can reach more than 95%. Effective filter dust in the air, pollen, and other pollutants, the filter less pollution. It can effectively extend the life of the purifier filter more than 1 , saving replacement costs. The filter screen used for the filter of the finished purifier can effectively increase the service life of the filter screen, so that your filter screen can truly reach the service life marked by the manufacturer. When the wind speed of 0.5m / s, wind resistance as low as 3.5pa, does not affect the wind speed. This filter is compatible with Mi air purifier 1/2 / Plus, or cut it into the appropriate size for air conditioners, windows, electric fans. 1. Filter , PM2.5, etc. 2. Used in conjunction with the HEPA filter, placed on the front of the HEPA filter, can effectively extend the life of the HEPA filter. White, soft, non-toxic, odorless, washable 1 or 2 , not to rub hard. Range of use:Modified for household air conditioners, fans, air circulation fans, air conditioners, exhaust fans, fans, etc. colour:white Material:cotton Package Contents: 4 * Filter cotton Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.