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Claim 1

A CARTRIDGE FOR A CARTRIDGE-TYPE FILTER HAVING A CONTAINER AND A COVER THEREFOR, THE COMBINATION INCLUDING A FORMAINOUS CORE HAVING RIDIG ANNULAR SPOOL END MEMBERS FIXED AT EACH END THEREOF, SAID CORE HAVING ITS OPPOSITE ENDS NECKED TO FORM END PORTIONS OF REDUCED DIAMETER, SAID RIGID ANNULAR SPOOL END MEMBERS HAVING INWARDLY DIRECTED COLLAR MEANS ADAPTED TO ENGAGE SAID NECKED END PORTIONS, THE ENDS OF SAID NECKED END PORTIONS BEING DISPLACED TO THE ORIGINAL DIAMETER OF SAID CORE TO THEREBY HOLD SAID END MEMBERS AND CORE TOGETHER, SAID NECK END PORTIONS BEING A PREDETERMINED DISTANCE APART SO AS TO HOLD SAID RIGID ANNULAR SPOOL END MEMBERS IN SPACED RELATION; AXIALLY OUTWARDLY DIRECTED FLANGES SURROUNDING THE OUTER PERIPHERY OF AND INTEGRAL WITH SAID CORE, SAID FILTERING MEMBERS; A FILTERING MEDIUM BETWEEN SAID ANNULAR SPOOL END MEMBERS AND SURROUNDING SAID CORE, SAID FILTERING MEDIUM BEING OF FELT HAVING AS A MAJOR PORTION THEREOF, SYNTHETIC FIBERS, SOME OF SAID FIBERS BEING MECHANICALLY INTERLOCKED WITH OTHERS; AND COMPRESSIBLE GASKET MEANS ON THE EXTERIOR FACES OF SAID ANNULAR SPOOL END MEMBERS EXTENDING AXIALLY BEYOND AND RESTRAINED AGAINST RADIAL EXPANSION BY SAID OUTWARDLY DIRECTED FLANGES WHEN PRESSURE IS APPLIED THERETO BY ASSEMBLING THE COVER TO SAID CONTAINER.