... to produce HEPA Could be classified five types: PP filter paper, glass fiber, compound PP+PET filter paper, ... Material:Thermosol3) Material: PP , PET or glassfiber filter paper4) Efficiency:99%, 99.97%. 99.999% efficiency ... not released into the air again.Hepa air filter Application:1)Hepa Vacuum Cleaner, Hepa air purifier, etc.2)FFU, ... , good quality and prompt delivery. Mini-pleat hepa air filters