Fortress Filtration Qty(10) Sediment 1 Micron 20" x 4.5" Water Filters RO/Cartridges/Big Blue/WVO Fortress Filtration Premium Water Filters Full Case of 10 Sediment Filters!! 1 Micron, 20" x 4.5" In Stock - Ready to Ship!! With Fortress Filtration products, you are being protected by the best!