vacuum cleaner bagsare of good endurance; Large volume of containing dust; From one layer to 5 layer; Filtration efficiency from 95% to HEPA grade 99.97% at 0.3um. It can be designed to be anti-bacterial, odor removal, kill mites . Testing standard: ASTM F1977-04Standard Test Method for Determining Initial, Fractional, Filtration Efficiency of a Vacuum Cleaner System1DIN 44956-2