Less is more.After being inspired by its warm, adaptable Alpha jacket, Castelli set out to create an even more minimal layer for winter riding that protected like a jacket and fit like a jersey. Sure, the jacket fits impeccably and protects against winter's harshest conditions without feeling like a mountaineering parka, but the brand knew it could pare the Alpha down even more to further serve its passion for minimalism. On the days when the warmth of a jacket is too much, or for cyclists who just don't like to wear too many layers, the Alpha Wind Jersey will block out gusts of wind and pelting rain without a second thought, with the streamlined, perfectly tailored fit that you'd expect from a Castelli jersey. Starting with the back panel, Castelli shields the area of your body most exposed to inclement weather on a bike with its proprietary Nano Warm fabric. Breathable and moisture wicking, the fabric will shed water without absorbing it, keeping you dry and warm. Your arms and chest receive protection in the form of Gore's 3-layer knit Windstopper 3 fabric, which blocks out wind and is treated with a DWR coating to repel water. Though it acts like a shell, Windstopper 150's knit construction allows it to provide ample stretch so that it doesn't inhibit your freedom of movement as you ride, and it continues to facilitate moisture transfer while blocking out the elements. Borrowing from the Alpha jacket's two-layer design, the jersey also features a Prosecco Stratus liner with dual front zippers, ideal for managing your body temperature as you heat up during a long climb. The liner breathes exceptionally well and creates airflow without exposing your base layer or bare skin to icy cold air — when you reach the chilly summit, zip the jacket back up to stay warm and dry on the descent. Castelli paid close attention to constructing the articulated collar to fit comfortably on and off the bike, and it included the same flat, raw-edge waist and wrists as the Alpha jacket that move with you without riding up or bunching, along with a silicone gripper at the waist to keep it in place. And if you notice the front external zipper doesn't look entirely straight, you're not imagining it. Castelli purposely designed an asymmetrical zipper to keep the jacket close to the skin, eliminating the likelihood of the puffy, bunched look that's so common in cold weather kit.