The MSR Guardian Gravity Water Purifier Replacement Cartridge restores flow rates to your Guardian Gravity Purifier System. It can be used to refresh your existing system or stored as an on-hand spare for peace of mind, assuring zero downtime and plenty of capacity when you need your purifier most. Encased in a rugged, military-grade housing, it’s two-stage design utilizes activated carbon and hollow-fiber technology to purifiy water from most any source, meeting NSF protocol P248 military testing standard for removing viruses (99.99%), bacteria (99.9999%), protozoa (99.9%), sediment and microplastics from “worst-case” water conditions, while reducing chemicals and unwanted taste and odors from your water. The replacement filter measures 9.5 x 2 inches and weighs 4.5 ounces. Made in the USA. Manufacturer’s 3-year limited warranty.