Streamlined, warm and weather protective, the Alpha Jacket is one of Castelli's premium designs and promises to change the way you think about cold weather defenses. It's constructed with Windstopper 150 fabric, an extremely lightweight, elastic, wind-blocking and water-repellent material. Inside, you'll find an insulated baselayer with ventilation and moisture-wicking properties. Castelli has detached the baselayer from the windproof fabric, so that you can open the windproof layer for venting and moisture evacuation without blasting your entire core with cold air. Both pieces work together to regulate temperature and comfort while keeping you drier. Raw-cut edge hem lays completely flat for improved aerodynamics and when you're down in the drops, it follows your body without binding or billowing. Raw edge wrist cuffs interface perfectly with gloves to keep drafts out and improve comfort. Articulated collar follows the bend in your neck, whether you're standing or riding in the lowest aero position. Perfect for moderate to extreme conditions, the Castelli Alpha Jacket gives you every reason to ride through the winter.