Introducing the world's most advanced portable purifier: the Guardian. Co-developed with the US military, it's been designed to be the safest, easiest way to purify water - wherever you are in the world.With a Hollow Fibre cartridge it removes viruses, protozoa, bacteria and sediment from even the dirtiest water. On each stroke the purifier uses 10% of its water to flush the contaminants from its filter, ensuring a fast flow rate regardless of water conditions. Fast, durable and long-lasting, it will treat 10,000+ litres of water, purifying 2.5 litres per minute without need for chemicals or batteries.With a rugged construction, small pack size and weighing less than 500 grams, it's an exceptional choice for international travel, long-distance backpacking trips and expedition use. MSR Guardian Purifier