These are new in bag msr filter hang bags, they are designed to scope out water then you hang the bag in a tree and a inline filter filters the water before your hydration bladder or other clean container.

It is compatible with the msr military inline water filter, the msr thru-link inline water filter or a Sawyer mini(as pictured). Makes filtering water super easy, no pumping or squeezing, let gravity do the work. They have a pinch valve at the end to stop water from draining out of the tube when not in use. My estimation is they hold about a gallon of water up to the fill line.

This listing is for just the hang bag and does not include the filter