Patent ID: 6878283

Claim:
A filter cartridge assembly comprising: a tubular housing having an inner wall, an outer wall, a first end, and a second end, said inner wall including at least a first section, a second section, and a third section, said first section having a first length in a direction from said first end to said second end and a first average inner diameter, said second section having a second length in a direction from said first end to said second end and a second average inner diameter that is smaller than said first average inner diameter, said third section having a third length in a direction from said first end to said second end and a third average inner diameter that is smaller than said second average inner diameter, wherein the inner wall of said tubular housing includes a first shoulder at the intersection of said first section and said second section and a second shoulder at the intersection of said second section and said third section; and a plurality of filter media sections within the tubular housing and radially contained by said inner wall, each of said plurality of filter media sections having a filter media composition, wherein at least one of said plurality of filter media sections has a length in a direction from said first end to said second end that includes at least portions of at least two of said lengths of the inner wall sections such that said at least one of said plurality of media sections traverses at least one of said shoulders.