A special name Hoover gives to their high filtration dustbags. They are also known as Allergen Filtration dustbags. According to Hoover, this dustbag Traps 99% of particles down to 5 microns! Filters a wide range of airborne particles including many pollens, spores, other allergens and dust mites. Ideal for many with dust related or allergic discomforts. Electrostatically charged liner enhances the capture of extremely fine particles.