MSR's 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. 4.7"L x 3.5"W x 8.2"H. Weight: 1.1 lbs.Manufacturer model #: 02370. Single-step purification for all water types Requires no chemicals Treats up to 10,000 liters Pumps 2.5 liters per minute Hollow-fiber technology blocks the tiniest waterborne threats Self-cleaning system doesn't require backflushing or filter scrubbing Flushes contaminants in the filter back to water source with every stroke Meets NSF protocol P248 testing standard used by the U.S. military