Replacement Big Blue Water Filters : Sediment,Carbon & GAC+KDF 85 Block : 4.5" x 20" Top Quality Replacement which fits most Big Blue 20" Whole House Systems. Includes: 1PCS Sediment Filter (5 Micron), 1PCS Carbon Block (5 Micron) & 1 GAC Carbon + KDF 85. Cartridges are designed for high-flow water filtration applications. Perfect for well water. Unique, wide cartridges are capable of filtering enough water for a house, apartment or office.