.Washable and reusable .Low resistance    .Excellent flame retardant    .Flexible    .Economical and practical Application: ≥5μm , Filter dust               (especially used in the train or the subway, where the place has air-conditioner),  pre-filter through air filter program Type: pads or rolls size Media: synthetic fiber with gradual density, Washable: about 2-3 times EN779 class: G2 Average arrestance:75%（ASHRAE52.1-1992） EUROVENT4/5 class: EU2 DIN53438 Non-flammability Standard: F1 Final resistance: (suggested) 100Pa-(max)200Pa Max. Dust holding capacity: 430g/sq.m Temperature resistance: 100degree