Electrostatic electret filter using 3D process, less wind resistance, cleanability. Effectively extend the of three to five times. The size of the product for all types of air filter, applicable to all types of air-conditioning on-hook car filter. It is used in the pre-filter of the finished filter to effectively increase the service life of filter, so that of your home can truly reach the service life marked by the manufacturer. QUALITY GUARANTEE: Best quality. Our Brand is dedicated to provide high standard products，we have confidence in our products and provide after sale support,if you have products quality issues, please contact us.