An air filtration media pack (301, 302, 402, 502, 602) comprising: (a) a plurality of layers of single facer media (5, 117, 137, 147) wherein the layer of single facer media comprising a fluted sheet (3, 43, 70, 80, 90, 112, 122, 142), a facing sheet (4, 44, 72, 73, 82, 83, 92, 93, 111, 113, 121, 123, 141, 143), and a plurality of flutes (11, 15) extending between the fluted sheet and the facing sheet and having a flute length extending from a first face (304, 414) of the filtration media pack to a second face (306, 416) of the filtration media pack, wherein the fluted sheet comprises repeating internal peaks (114, 116, 124, 144) facing toward the facing sheet and repeating external peaks (115, 119, 125, 145) facing away from the facing sheet, and wherein a cord length refers to a straight line distance from a center point of an internal peak and a center point a of an adjacent external peak; and the media length defines an arcuate media length for a flute over a distance defining a period length or interval of a media construction; (b) a first portion of the plurality of flutes being closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes being closed to unfiltered air flowing out of the second portion of the plurality of flutes so that air passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the air; and characterized in that (c) (i) at least a portion of the plurality of flutes exhibit a media-cord percentage of at least about 6.2%, wherein the media-cord percentage is ((1⁄2 x media length - cord length)/cord length) x 100; and (ii) the internal peaks or the external peaks or both have a radius of less than 0.25 mm; and (iii) wherein at least a portion of the plurality of flutes exhibit a flute width height ratio of greater than about 2.2 or less than about 0.45; and (iv) the media pack has a volume asymmetry so that a volume on one side of the media pack is greater than a volume on another side of the media pack by at least 10%, and (v) at least a portion of the plurality of flutes are tapered. (a) a plurality of layers of single facer media (5, 117, 137, 147) wherein the layer of single facer media comprising a fluted sheet (3, 43, 70, 80, 90, 112, 122, 142), a facing sheet (4, 44, 72, 73, 82, 83, 92, 93, 111, 113, 121, 123, 141, 143), and a plurality of flutes (11, 15) extending between the fluted sheet and the facing sheet and having a flute length extending from a first face (304, 414) of the filtration media pack to a second face (306, 416) of the filtration media pack, wherein the fluted sheet comprises repeating internal peaks (114, 116, 124, 144) facing toward the facing sheet and repeating external peaks (115, 119, 125, 145) facing away from the facing sheet, and wherein a cord length refers to a straight line distance from a center point of an internal peak and a center point a of an adjacent external peak; and the media length defines an arcuate media length for a flute over a distance defining a period length or interval of a media construction; (b) a first portion of the plurality of flutes being closed to unfiltered air flowing into the first portion of the plurality of flutes, and a second portion of the plurality of flutes being closed to unfiltered air flowing out of the second portion of the plurality of flutes so that air passing into one of the first face or the second face of the media pack and out the other of the first face or the second face of the media pack passes through media to provide filtration of the air; and (c) (i) at least a portion of the plurality of flutes exhibit a media-cord percentage of at least about 6.2%, wherein the media-cord percentage is ((1⁄2 x media length - cord length)/cord length) x 100; and (ii) the internal peaks or the external peaks or both have a radius of less than 0.25 mm; and (iii) wherein at least a portion of the plurality of flutes exhibit a flute width height ratio of greater than about 2.2 or less than about 0.45; and (iv) the media pack has a volume asymmetry so that a volume on one side of the media pack is greater than a volume on another side of the media pack by at least 10%, and (v) at least a portion of the plurality of flutes are tapered. (i) at least a portion of the plurality of flutes exhibit a media-cord percentage of at least about 6.2%, wherein the media-cord percentage is ((1⁄2 x media length - cord length)/cord length) x 100; and (ii) the internal peaks or the external peaks or both have a radius of less than 0.25 mm; and (iii) wherein at least a portion of the plurality of flutes exhibit a flute width height ratio of greater than about 2.2 or less than about 0.45; and (iv) the media pack has a volume asymmetry so that a volume on one side of the media pack is greater than a volume on another side of the media pack by at least 10%, and (v) at least a portion of the plurality of flutes are tapered.