An air filter cartridge comprising: (a) a filter media surrounding an open filter interior; (i) the filter media having first and second ends (3, 4); (b) a first end piece positioned at the first end of the filter media; (i) the first end piece having a flow aperture therethrough; (c) the first end piece includes a first housing seal member thereon; (d) a second end piece positioned at the second end of the filter media; (i) the second end piece is closed, and has no aperture therethrough, in direct flow communication with the open filter interior; (ii) the second end piece includes a receiver projection extending into the open filter interior a distance, from the filter media second end toward the filter media first end, corresponding to at least 10% of a distance from the filter media second end to the filter media first end; the receiver projection defining a receiver recess at an opposite side thereof, from the open filter interior; (e) the filter media first end defining a first media end outer perimeter at a location adjacent the first end piece; (f) the filter media second end defining a second media end outer perimeter at a location adjacent the second end piece; (i) the first and second media outer perimeters being eccentrically aligned with respect to one another; (g) the first media outer perimeter has a first dimension of length; and (h) the second media outer perimeter has a second dimension of length; (i) the first dimension of length being within 90-110% of the second dimension of length. (a) a filter media surrounding an open filter interior; (i) the filter media having first and second ends (3, 4); (i) the filter media having first and second ends (3, 4); (b) a first end piece positioned at the first end of the filter media; (i) the first end piece having a flow aperture therethrough; (i) the first end piece having a flow aperture therethrough; (c) the first end piece includes a first housing seal member thereon; (d) a second end piece positioned at the second end of the filter media; (i) the second end piece is closed, and has no aperture therethrough, in direct flow communication with the open filter interior; (ii) the second end piece includes a receiver projection extending into the open filter interior a distance, from the filter media second end toward the filter media first end, corresponding to at least 10% of a distance from the filter media second end to the filter media first end; the receiver projection defining a receiver recess at an opposite side thereof, from the open filter interior; (i) the second end piece is closed, and has no aperture therethrough, in direct flow communication with the open filter interior; (ii) the second end piece includes a receiver projection extending into the open filter interior a distance, from the filter media second end toward the filter media first end, corresponding to at least 10% of a distance from the filter media second end to the filter media first end; the receiver projection defining a receiver recess at an opposite side thereof, from the open filter interior; the receiver projection defining a receiver recess at an opposite side thereof, from the open filter interior; (e) the filter media first end defining a first media end outer perimeter at a location adjacent the first end piece; (f) the filter media second end defining a second media end outer perimeter at a location adjacent the second end piece; (i) the first and second media outer perimeters being eccentrically aligned with respect to one another; (i) the first and second media outer perimeters being eccentrically aligned with respect to one another; (g) the first media outer perimeter has a first dimension of length; and (h) the second media outer perimeter has a second dimension of length; (i) the first dimension of length being within 90-110% of the second dimension of length. (i) the first dimension of length being within 90-110% of the second dimension of length.