1) High efficiency HEPA grade, with minimum efficiency of 99.97% at 0.3 microns (based on D.O.P. tes 1) High efficiency HEPA grade, with minimum efficiency of 99.97% at 0.3 microns (based on D.O.P. tests)2) One layer, two layers and multi-layers3) Different weight melt-blown, which has good air permeability and dust retention filtration media for Vaccum cleaner Bag