Capable of capturing the most minute particles, Guardair's Absolute ULPA (Ultra Low Penetration Air) Cartridge Filter meets the highest industry standards for air filtration - 99.97% efficiency for particles up to 0.1 microns. Ideal for working with allergens, mold, pollen, superfine powders, etc. Cloth pre-filter bag provides extra stage of filtration extending the life of the cartridge filter. Fits all 55 Gallon and 30 Gallon Guardair Drum Vacuums and Vacuum Generating Heads. Replacement part.