The Sawyer Products Squeeze Bag Filter, 0.5, 1 and 2 Liter are an excellent, light, pack-away-small take-anywhere water filtration system. Simply fill the bag with water from any source and screw on the lid. Then open the push/pull on/off tap and squeeze the water directly into your mouth or into any water bottle or container. The 0.1 micron hollow fiber water filter membrane removes 99.999% of bacteria like salmonella and E.coli and protozoa like giardia to provide safe, healthy drinking water. The filter comes with cleaning syringe and instructions so you can easily maintain it and increase its life.