Fortress Filtration Qty(6) Carbon 5 Micron 20" x 4.5" Coconut Water Filters RO/Cartridges/Case/Block/GAC Fortress Filtration Premium Water Filters Full Case of 6 Coconut Carbon Filters!! 5 Micron, 20" x 4.5" In Stock - Ready to Ship!! - These are standard sized filters and fit most 10" x 4.5" water filter housings. With Fortress Filtration products, you are being protected by the best!