MSRs Guardian Portable Water Purifier offers reliable single-step purification for all water types anywhere in the world. Unlike other water purifiers on the market, the Guardian requires no chemicals to remove viruses, bacteria, protozoa and particulates. Fast, simple and safe, it treats up to 10,000 liters and pumps 2.5 liters per minute. Hollow-fiber technology blocks the tiniest waterborne threats and withstands freezing and drops. Patent-pending self-cleaning system never requires backflushing or filter scrubbing to maintain flow. With every stroke, the purifier uses 10% of the water to flush the contaminants in the filter back into the water source. Meets NSF protocol P248 testing standard used by the U.S. military. Made in USA. 4.7L x 3.5W x 8.2H. Wt: 1.1 lbs. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Filters.