MSR Guardian Filter Cartridge Replacement - This replacement filter cartridge restores your Guardian Purifier's flow rate, and lasts up to 10,000+ liters. Removes viruses, bacteria, protozoa, and particulates, like dirt and sediment This replacement filter cartridge restores your guardian purifier's flow rate and Lasts up to 10,000+ litersRemoves Viruses, bacteria, protozoa, and particulates, like dirt and sedimentHollow fibers provide the most reliable means for purification in many real-world situationsMade in the USA of US and imported materialsBPA Free