(3 Pack) 3M Aqua-Pure 63597174C ORing [Genuine Captain O-Ring Part] Includes 3 replacement o-rings (also called seals or gaskets) to repair your leaking water filter housing Fits Housings: AP11S, AP11T, AP12S, AP12T, AP26T, AP51T, AP101S, AP101T, AP102S, AP102T, AP110, etc Replace your O-Ring with every 3rd filter change to prevent leaks O-Ring is approximately 3.5" Inside Diameter x 3.75" Outside Diameter Manufactured and warrantied by Captain O-Ring LLC