HEPA filter is filtrated 0.1 micron and 0.3 micron efficiency of 99.7%, HEPA , airflow go out in low resistance. It has a particle removal efficiency of more than 99.97% for particles with a diameter of 0.3 μm (1/200 of the hair diameter) and is the most effective filtration medium for pollutants such as smoke, dust and bacteria. HEPA points PP filter paper, glass fiber, PP composite PET filter paper, melt-blown polyester non-woven fabrics and melt-blown glass fiber five materials. Frame is made of cardboard or plastic. Features: Large air resistance, dust holding capacity, high filtration precision, can be processed into various sizes and shapes according to customer needs, suitable for different models.