WaterChef UR90 Under-Sink Filter Replacement Cartridge (for U9000 Filtration Systems) Superior Performance and Taste Powerful Big Block Filtration Technology Huge 1,000 GALLON Rated Capacity Certified by NSF International (ANSI/NSF Standards 42 & 53) Proprietary 3-Ply, Pleated Pre-Filter for Increased Dirt Holding Capacity and Longer Cartridge Life