MSR Guardian Purifier Cartridge Replacement

Outdoorplay says:
The MSR Guardian Filter Cartridge Replacement restores your Guardian Purifier's flow rate. Lasting up to 10, 000+ liters, it removes viruses, bacteria, protozoa and particulates like dirt and sediment. Make sure you have yourself covered the next time you're spending long hours on the trail. Removes viruses, bacteria, protozoa, and particulates like dirt & sediment Cartridge replacement indicator Meets NSF protocol P248, testing standard used by U.S. military