The Aqualine Dry Bag should be considered an essential accessory for your next adventure,featuring welded seams and a roll top closure to keep water out and your kit protected. All Aqualine's bags are constructed with welded seams and nylon/PVC, providing the user with extra strengh and durability.These drybags can also be used to create a waterproof liner inside any rucksack- just choose the size of dry bag closest to the volume of your rucksack. Bear Grylls even suggests that these can be used as waterfloats.