The MSR Guardian Purifier is a water filter and purifier which is able to not only remove unwanted particles from a water source but also bacteria, protozoa and viruses. Originally designed for the US military it is able to pump 2.5 litres per minute through an advanced hollow fibre filter and doesn't require any chemicals, bulbs or batteries.

It's easy to use; just place the end of the hose into the water source, connect the base of the filter to a wide mouthed bottle (fits Nalgene wide mouth bottles) and start pumping. Another great innovation on the Guardian filter is the self cleaning feature; each pump stroke self cleans the filter without impeding the flow rate so that you never have to backflush or remove the filter for cleaning. It's able to pump up to 10,000 litres of water before the cartridge needs replacing and the entire purifier has been tested to withstand heavy use, harsh environments and even dropping it onto a concrete floor from 6ft. For backpacking, travelling or trekking the Guardian Purifier is a brilliant solution.

MSR Guardian Purifier Features

• Removes viruses, bacteria and protozoa
• 0.02 micron filter size
• Self cleaning
• 10,000 litre cartridge life
• Cartridge replacement indicator
• 2.5L per min flow rate
• Tough, durable construction