Frame:galvanized steel, aluminium, stainless steelï¼?Cardboard Filter media:activated carbon particles or synthetic fiber, fiberglass Grids:aluminium mesh, galvanized steel mesh Thickness available: 22mm, 45mm, 95mm etc. Efficiency:Trapping 40-60% of >=5.0 �µm particles EN 779 Class:G2-G4 Humidity: â?¤99%RH Packing : inner package is carton box , outer package is pallet or demands customer's need Port :QingDao Application Cardboard Frame Pre Air Filter can be widely used in pre-filter system for clean rooms, HEPA air filters, air compressors, central air-conditioning fresh air handling unit and ventilation systems, and computer rooms dedicated constant temperature and humidity air conditioning unit.