Few things are more refreshing than a drink of water on a hot day. The latest and greatest way Hydrapak is keeping that water extra cool is using PrimaLoft—the same fluffy material that keeps mountaineers from freezing to death in the snow.

In recent years PrimaLoft—a synthetic insulation—has become increasingly popular in serious cold weather gear because it's soft, lightweight, water-repellent, and most importantly, is a fantastic insulant. Which is exactly why Hydrapak sandwiches the material between the double plastic walls of its Woolly Mammoth insulated water bottle. Not only does it help keep cold drinks colder for longer, it will also help warm beverages stay toasty, and even prevent liquids from freezing altogether when its used in frigid climates. Not bad for a 20oz. bottle that will sell for just $16 when it's available this Fall—cheaper than comparatively-sized metal bottles. [Hydrapak via GearJunkie]