20-Pack Replacement Puromax PC4 Activated Carbon Block Filter Reduce water bottle waste and save money while also helping the environment by using water filters. NSF certified, 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. For the highest quality water and best contaminant reduction replace the filter every 6 months. For a list of other compatible models, please click here. SKU: WF-RO-CB10-20PK-DL533