G4 Pre Washable Air Filter Panel Aluminum Frame Pre Air Filter Capture Particles larger than 5μm and other suspended matter. Style: Pleated, Panel, Bag Frame: Cardboard or Aluminum Filtering Media: Special Non-woven fabric, metal mesh or activated carbon Efficiency: 35% ~ 95% @ 5μm (G4 ~ F5) Application: Used for primary air filtration Airkey factory: