A filter replacement kit comprising: a replacement filter cartridge (4000; 4002; 4004; 4006; 4008; 4010) having a centerline axis extending in a longitudinal direction thereof, the replacement filter cartridge comprising: a filter body (304; 504); a filter media disposed within the filter body; a neck portion (302; 4100; 4200; 4300; 4400; 4500; 4600) having a fluid inlet and a fluid outlet; and a cartridge engagement mechanism on the neck portion for engaging manifold attachment members (356a, 356b) of a manifold assembly (12; 332), wherein the manifold attachment members (356a, 356b) each comprise a manifold engagement surface comprising a first horizontal portion (360a, 360b), a second horizontal portion (364a, 364b), and an angled portion (362a, 362b) disposed between and joining the first horizontal portion (360a, 360b) to the second horizontal portion (364a, 364b), the cartridge engagement mechanism comprising at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) which provide at least one filter engagement surface, wherein the at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) are spaced axially and circumferentially apart from each other with respect to the centerline axis; and compatibility indicia (4120; 4220; 4320; 4420; 4520; 4620), wherein the compatibility indicia indicates that the replacement filter cartridge (14; 300; 500) is a compatible replacement for at least one replaceable filter cartridge, wherein the at least one replaceable filter cartridge (14; 300; 500) includes a replaceable filter engagement mechanism including a pair of opposed and identically configured multi-stage filter attachment members (310a, 310b) each providing a replaceable filter engagement surface, the multi-stage filter attachment members (310a, 310b) each having a first horizontal portion, a second horizontal portion, and an angled portion disposed between and joining the first horizontal portion to the second horizontal portion, wherein the manifold attachment members (356a, 356b) are configured to be congruent to the multi-stage filter attachment members (310a, 310b), and wherein the filter engagement surface is non-congruent to the replaceable filter engagement surface. a replacement filter cartridge (4000; 4002; 4004; 4006; 4008; 4010) having a centerline axis extending in a longitudinal direction thereof, the replacement filter cartridge comprising: a filter body (304; 504); a filter media disposed within the filter body; a neck portion (302; 4100; 4200; 4300; 4400; 4500; 4600) having a fluid inlet and a fluid outlet; and a cartridge engagement mechanism on the neck portion for engaging manifold attachment members (356a, 356b) of a manifold assembly (12; 332), wherein the manifold attachment members (356a, 356b) each comprise a manifold engagement surface comprising a first horizontal portion (360a, 360b), a second horizontal portion (364a, 364b), and an angled portion (362a, 362b) disposed between and joining the first horizontal portion (360a, 360b) to the second horizontal portion (364a, 364b), the cartridge engagement mechanism comprising at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) which provide at least one filter engagement surface, wherein the at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) are spaced axially and circumferentially apart from each other with respect to the centerline axis; and a filter body (304; 504); a filter media disposed within the filter body; a neck portion (302; 4100; 4200; 4300; 4400; 4500; 4600) having a fluid inlet and a fluid outlet; and a cartridge engagement mechanism on the neck portion for engaging manifold attachment members (356a, 356b) of a manifold assembly (12; 332), wherein the manifold attachment members (356a, 356b) each comprise a manifold engagement surface comprising a first horizontal portion (360a, 360b), a second horizontal portion (364a, 364b), and an angled portion (362a, 362b) disposed between and joining the first horizontal portion (360a, 360b) to the second horizontal portion (364a, 364b), the cartridge engagement mechanism comprising at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) which provide at least one filter engagement surface, wherein the at least two multi-stage filter attachment members (4110; 4210; 4310; 4410; 4510; 4610) are spaced axially and circumferentially apart from each other with respect to the centerline axis; and compatibility indicia (4120; 4220; 4320; 4420; 4520; 4620), wherein the compatibility indicia indicates that the replacement filter cartridge (14; 300; 500) is a compatible replacement for at least one replaceable filter cartridge, wherein the at least one replaceable filter cartridge (14; 300; 500) includes a replaceable filter engagement mechanism including a pair of opposed and identically configured multi-stage filter attachment members (310a, 310b) each providing a replaceable filter engagement surface, the multi-stage filter attachment members (310a, 310b) each having a first horizontal portion, a second horizontal portion, and an angled portion disposed between and joining the first horizontal portion to the second horizontal portion, wherein the manifold attachment members (356a, 356b) are configured to be congruent to the multi-stage filter attachment members (310a, 310b), and wherein the filter engagement surface is non-congruent to the replaceable filter engagement surface.