pocket air filter for electronics: 1.high efficiency 2.lower resistance 3.high dirt holding capacity 4.each be tested The pocket filter offers high efficiency filtration,superior dust holding capacity and low resistance.Out Frame : aluminum alloysFiltr media: Glassfiber /SynheticEfficiency(dust –spot): 85%-95%En779 class: G2, G3, G4, F5, F6, F7, F8