Air filtration media pack, filter element, air filtration media, and methods

An air filtration media pack is provided having a plurality of layers of single facer media. The layer of single facer media includes a fluted sheet, a facing sheet, and a plurality of flutes extending between the fluted sheet and the facing sheet and having a flute length extending from a first face of the filtration media pack to a second face of the filtration media pack. A first portion of the plurality of flutes are closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes are closed to unfiltered air from flowing out of the second portion of the plurality of flutes so that air passing into one of the first face and the second face of the media pack and out the other of the first face and the second face of the media pack passes through media to provide filtration of the air. The fluted sheet includes repeating internal peaks facing toward the facing sheet and repeating external peaks facing away from the facing sheet. In addition, the fluted sheet can include at least one ridge extending along at least 50% of the flute length between an internal peak and an adjacent external peak. Additional characterizations of an air filtration media pack, air filtration media, and methods of making and using are provided.