It is used in the pre-filter of the finished purifier filter to effectively increase the service life of filter, so that the filter of your home can truly Suitable for: air purifier 2 / 1, or other brands of air purifier, air conditioning central air conditioning inlet, anti-fog, etc.Filter Cotton only, other accessories in the picture is not included reach the service life marked by the manufacturer Electrostatic electret filter using process, less resistance, cleanability Effectively extend the filter life of three to five times The size of the product for all types of air purifier HEPA filter, applicable to all types of air-conditioning on-hook car filter