Packyourbags Travel Store stocks a wide of hydration system products including hydration bladders, foldable water bags, water bottles, hydration packs and more. Hydration packs are small backpacks that contain a water bladder for water, with a tube and mouthpiece to get water to your mouth. We also sell hydration bladders separately. These hydration bladders are designed to be integrated into many different backpacks or other carried bags making them great for avoiding dehydration whilst running and other outdoor activities.