The water filter straw is made up of 0.01 ?m hollow fiber ultrafiltration membrane, Activated carbon fiber, and double PP Cotton. Just hang on a tree or put the gravity water bag in a high place, hands-free filtration, enjoy effort-free (no pumping, no squeezing) filtered water within minutes. : As a necessity for outdoor water purification, the Burtrail Gravity Water Filter is applicable to camping, hiking, backpacking, emergency preparedness (rainstorms, floods, earthquakes, hurricane, etc.) Features: High Efficiency Filtration: The water filter straw is made up of 0.01 ?m hollow fiber ultrafiltration membrane, Activated carbon fiber, and double PP Cotton. It filters about 600 milliliters per minute. The entire water filtration system is made of food-grade materials Easy to Use: Just hang on a tree or put the gravity water bag in a high place, hands-free filtration, enjoy effort-free (no pumping, no squeezing) filtered water within minutes. The operation of this gravity-fed water filtration system is remarkably straightforward Easy Maintenance: Wide open gravity water bag, water filling and flushing are very fast and convenient. The water filter straw backwash design, Insert a plastic bottle into the outlet of the filter for backwashing, no need for an extra syringe Multi Scene Application: As a necessity for outdoor water purification, the Burtrail Gravity Water Filter is applicable to camping, hiking, backpacking, emergency preparedness (rainstorms, floods, earthquakes, hurricane, etc.) to meet the emergency water demand in a variety of situations Portable and Lightweight: No cumbersome fittings and lightweight. Easy carrying survival water filtration system when putting all the parts in the organizer bag Package Includes: 1 Camping Water Filter Purifier Listing and template services provided by inkFrog