Composite net pleated air filter The composite net pleated air filter is suitable for the initial filtration of air conditioner and ventilation systems, filtration of the returned air in the clean chambers and pre-filtration for the partial high-effect filtration systems. It has been broadly used in various industries, to include electronics, electric appliances, aviation and aerospace, automobiles, pharmaceuticals, biological engineering, environmental protection, telecommunication, banks, intelligent buildings, hotels, restaurants, etc.