Peeking in the packs of adventurers all over the world who have wandered to hot or cold climates would most certainly reveal a few Water Bottle Parkas. And the people carrying these packs would probably be well-hydrated! A Water Bottle Parka will keep the heat where it should be! It will prevent a climber's bottle from freezing all day long in Himalayan cold or keep juice refreshingly cool for several hours of Sonoran heat. Also works great for protecting cylindrical items like camera lenses. Easy attachment to a pack.