Updated for 2017: The supreme ease of the AutoFlow Gravity Filter has converted many backcountry travelers to pump-free water filtration. Now, it offers the luxury of effortless water storage and filtration in a more compact, lightweight and streamlined system. Efficient hollow fiber technology filters up to 1.75 liters per minute, and quick and easy tool-free cleanings maintain high flow rates on extended expeditions. Choose the 4-liter system for groups and basecamps. The 2-liter system is perfect for backpacking pairs.