The MSR Autoflow XL 10L Gravity Filter is a larger version of MSR's ever-so-convenient gravity filter, appropriately sized for large groups of backpackers and campers, or two backpackers for a full day without refilling down by the river. This filter lets gravity do all the work and cleans nearly two liters of water per minute. The adapter end piece fits onto most standard water bottles and reservoirs. It's field cleanable too, so you can remove all the bacteria, protozoa, and sediment that's been filtered out and have a filter that's good as new in minutes.