O-Ring-HB for APEC 10″ or 20” BB Big Blue or Clear Water Filter Housing (4 Pack) Product Features: O-Ring Part Number: O-RING-HB Compatible with APEC 10” and 20” BB (Big Blue) and Clear Water Filter Housings. Includes Big & Compact Blue Housings: HBB-20 series; HBB-10 series (input sizes: 3/4″, 1″, 1.5″); Clear Housings: HBC-20 series; HBC-10 series (input sizes: 3/4″, 1″, 1.5″); Big Duo/Trio Housing Sets; and CB1, CB2, CB3 filter bundles. Approximate O-Ring Dimensions: 5-1/2” inside diameter, 5.83” (slightly over 5-3/4”) outside diameter, and just under 3/16” thickness. Package contains four (4) o-rings (also called gaskets or seals). O-Rings should be replaced when changing the filter cartridge to avoid possible water leakage. Molded from NSF 61 certified buna-n rubber for safe and clean drinking water. Manufactured and warrantied by Captain O-Ring LLC. Proudly assembled in the USA! Replace your old, worn, leaking water filter o-ring with Captain O-Ring’s replacement O-RING-HB o-rings. The O-RING-HB o-ring is compatible with APEC Big Blue HBB-20 series and HBB-10 series (input sizes: 3/4″, 1″, 1.5″); Big Clear Housings HBC-20 series and HBC-10 series (input sizes: 3/4″, 1″, 1.5″); Big Duo/Trio Housing Sets; and CB1, CB2, CB3 filter bundles. Approximate O-Ring Dimensions: 5-1/2” inside diameter, 5.83” (slightly over 5-3/4”) outside diameter, and just under 3/16” thickness. Package contains four (4) o-rings (also called gaskets or seals). Replace your old o-ring and have spares on hand for future filter changes with this handy 4-pack. Molded from NSF 61 certified buna-n rubber for safe and clean drinking water. Manufactured and warrantied by Captain O-Ring LLC. Proudly assembled in the USA!