Since 1862, Mammut has been designing technical mountaineering and ski gear for athletes who crave high-altitude adventures. The Swiss company packs a heap of thoughtful tech into its all-new Alvier Flex Down Jacket, formulated specifically as a layering piece for skiers. This hooded full-zip has a slim, athletic fit and low-profile construction that uses thinner material on the sleeves and underarms to promote movement and manage moisture. It weighs just 470 grams—a tad more than a baseball—and is woven with an ultra-stretchy fabric for a dynamic fit.