4-Pack Replacement Rainsoft 21179 Activated Carbon Block Filter - Universal 10 inch Filter for Rainsoft 21179 Three Stage RO System - Denali Pure Brand Replacement Rainsoft 21179 Activated Carbon Block Filter, Quantity: 4 Replacement Rainsoft 21179 Activated Carbon Block Filter Coconut shell carbon, universal 10 inch activated carbon block filter. Improves taste and clarity while retaining beneficial nutrients by reducing chlorine, fine sediment, odor, silt, rust. Removes undesirable and possibly harmful waterborne contaminants, particles, chemicals and microorganism. Reduce water bottle waste and save money while also helping the environment by using water filters. For the highest quality water and best contaminant reduction replace the filter every 6 months. On Sale for a Limited Time!