Filter media (100, 200, 1308) comprising: a first sheet of filter media having a first side and a second side and pleated along a plurality of bend lines to form a plurality of wall segments; the plurality of wall segments comprising a first set of wall segments alternately sealed to each other at the first side to define: a first set of tetrahedron channels having open first ends at an upstream air inlet of the filter media, such that, in use, air to be filtered flows into the filter media through the open first ends, and a second set of tetrahedron channels interdigitated with the first set of tetrahedron channels and having closed first ends at the upstream air inlet; the plurality of wall segments comprising a second set of wall segments alternately sealed to each other at the second side to define: a third set of tetrahedron channels having closed second ends at a downstream air outlet of the filter media, and a fourth set of tetrahedron channels interdigitated with the third set of tetrahedron channels and having open second ends at the downstream air outlet, such that, in use, filtered air flows out of the filter media through the open second ends, the plurality of wall segments thereby defining air flow channels, and, in use, an air flow direction, through the filter media between the upstream air inlet and the downstream air outlet; and a second sheet of filter media extending across the first sheet of filter media, characterized in that the second sheet of filter media comprises a plurality of embossments arranged in an interrupted straight line pattern, each of the plurality of embossments form a raised surface configured to maintain a separation distance between the second sheet of filter media and an adjacent sheet of filter media, the plurality of embossments arranged at an angle Φ with respect to an X-Y axis that defines a plane of the second sheet of filter media, wherein the tetrahedron channels (50, 52, 58, 60) extend along an axial direction, wherein the Y axis is aligned with the axial direction and the X axis is aligned with a lateral direction which is perpendicular to the axial direction, wherein the angle Φ is between 0 and 60 degrees relative to the lateral direction. a first sheet of filter media having a first side and a second side and pleated along a plurality of bend lines to form a plurality of wall segments; the plurality of wall segments comprising a first set of wall segments alternately sealed to each other at the first side to define: a first set of tetrahedron channels having open first ends at an upstream air inlet of the filter media, such that, in use, air to be filtered flows into the filter media through the open first ends, and a second set of tetrahedron channels interdigitated with the first set of tetrahedron channels and having closed first ends at the upstream air inlet; a first set of tetrahedron channels having open first ends at an upstream air inlet of the filter media, such that, in use, air to be filtered flows into the filter media through the open first ends, and a second set of tetrahedron channels interdigitated with the first set of tetrahedron channels and having closed first ends at the upstream air inlet; the plurality of wall segments comprising a second set of wall segments alternately sealed to each other at the second side to define: a third set of tetrahedron channels having closed second ends at a downstream air outlet of the filter media, and a fourth set of tetrahedron channels interdigitated with the third set of tetrahedron channels and having open second ends at the downstream air outlet, such that, in use, filtered air flows out of the filter media through the open second ends, a third set of tetrahedron channels having closed second ends at a downstream air outlet of the filter media, and a fourth set of tetrahedron channels interdigitated with the third set of tetrahedron channels and having open second ends at the downstream air outlet, such that, in use, filtered air flows out of the filter media through the open second ends, the plurality of wall segments thereby defining air flow channels, and, in use, an air flow direction, through the filter media between the upstream air inlet and the downstream air outlet; and a second sheet of filter media extending across the first sheet of filter media, characterized in that the second sheet of filter media comprises a plurality of embossments arranged in an interrupted straight line pattern, each of the plurality of embossments form a raised surface configured to maintain a separation distance between the second sheet of filter media and an adjacent sheet of filter media, the plurality of embossments arranged at an angle Φ with respect to an X-Y axis that defines a plane of the second sheet of filter media, wherein the tetrahedron channels (50, 52, 58, 60) extend along an axial direction, wherein the Y axis is aligned with the axial direction and the X axis is aligned with a lateral direction which is perpendicular to the axial direction, wherein the angle Φ is between 0 and 60 degrees relative to the lateral direction.