The Gravity system is a lightweight, robust solution for filtering large quantities of water. It uses Sawyer's Dual-Threaded MINI filter to remove impurities from up to 100, 000 gallons, making it ideal for backpacking, backcountry camping, and emergency preparedness. The MINI filter weighs just under 40 grams and removes 7 log (99.99999%) of all bacteria (like salmonella) as well as other harmful bacteria which causes cholera and E. coli and 6 log (99.9999%) of all protozoa such as giardia and cryptosporidium. EPA guidelines allow ten times more protozoa left in the water than the Sawyer MINI filter allows. The MINI also filters out 100% of microplastics. With threads on both sides you can screw the push/pull cap onto the MINI for easy on/off functionality while filtering. The dual-bag is also convenient and easily packable, and it doesn't require any pumping either. The bladder features a wide mouth cap that allows for fast and easy filling, as well as a convenient carry handle. To set up a gravity system, first fill the reservoir with water from any source (a lake, stream, pond, glacier, kitchen faucet, etc.). Hang the bag — from a tree, the back of your pack, or hold it up with your hand — and connect the MINI to the included hose and let gravity do its work. Water will flow through the MINI to produce fresh, clean water for drinking and cooking. This kit includes: One 1-gallon bladder, cleaning plunger, cleaning coupling, and a gravity hose with adapters.