MSR Guardian Purifier Cartridge Replacement 4" high 4" wide When the Time comes to replace the Hollow fiber filter on your guardian, the guardian filter cartridge replacements have you covered 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 Hollow fibers provide the most reliable means for purification in many real-world situations Made in the USA of US and imported materials