1. Innovative technology: Uses electrostatic filter material to effectively capture airborne particles larger than 0.2μm; dust filtration efficiency for 0.5μm particles exceeds 95%. 2. Extends filter life: Effectively captures dust, pollen, bacteria, and other airborne pollutants, reducing contamination of the main filter element and extending the air purifier filter’s service life by more than double. 3. Improves filter longevity: The pre-filter design increases the usable life of the filter, helping it reach the manufacturer-specified service life. 4. Low airflow resistance: At an air velocity of 0.5 m/s, pressure drop is as low as 3.5 Pa, ensuring minimal impact on airflow performance. 5. Compatible with Xiaomi Mi Air Purifier 1, 2, and Plus models. Can also be cut to fit air conditioners, windows, or electric fans. Filtration targets include soot and PM2.5. Designed for use with HEPA filters—install in front of the HEPA filter to extend its lifespan. Soft, non-toxic, odorless, and washable up to two times—avoid vigorous rubbing. Suitable for modified air purifiers, household air conditioners, fans, air circulation fans, exhaust fans, and similar devices. Color: White Material: Cotton Size: 70 x 30 cm Package includes: 40 pieces of filter cotton