Staying warm is easy when you stay dry, and Castelli's Mortirolo 3 Jacket combines both for stellar comfort. The Windstopper X-Fast fabric is the core of the Mortirolo's functionality: it's windproof and water-resistant to tackle the gnarliest weather conditions under the sun—or the clouds. The Warmer Back prevents overheating, so you stay temp-regulated as weather conditions change. For quick venting, you get a full-length Camlock zipper, not to mention zippered chest vents. It's topped off with three external rear pockets to stow your goodies, and reflective tabs to enhance low-light visibility.