Pollen window screens look no different from ordinary window screens.But unlike ordinary screens, this thin layer of film is filled with holes that are invisible to the naked eye.Each square centimeter is probably densely packed with millions of molecular-sized holes.Molecular-scale pores allow only molecules to pass through, so fine particles such as PM2.5, pollen can be blocked by the thin film without affecting the passage of molecular components such as carbon dioxide. It is used by spring and summer