This pack is a great material! Impenetrable to H20! As a waterproof stuff sack this bag is great! This bag is so waterproof I think the manufactures are having trouble finding glue that will connect firmly to the material. The shoulder straps of the backpack have come unglued from the pack and so the backpack feature of this pack has become useless. I took one hike 13 miles with 25 or so pounds worth of gear and the plastic piece that the glue is holding onto the pack is sliding out as to make the shoulder straps fall off. Some advise to the manufacture, build a hard frame pack and put one of these packs in it!!! Also reinforce the bottom of the pack with some of the urban backpack material. It is important when keeping things dry that it wont rip when setting the pack down on the ground next to a school desk or in the dirt with sharp sticks!