iSpring F12WCB32 20x2.5-Inch Replacement Cartridges for WCB32O and WCB32C, Water Filtration System, Set of 4 Fits most standard 20"-housing water filters and reverse osmosis systems (Not for big blue filter housings) Length: 20", O.D. = 2.5", I.D.= 1" Fits iSpring water filtration systems WCB32C, WCB32O Individually wrapped for freshness, Pack of 4 Lifetime support line 678-261-7611 from Alpharetta, GA USA