Elementory, my dear Watson.
In warm weather, you can throw on any old jersey and hit the road, confident that you'll stay warm and happy. Winter makes things a little tricker. You want to be warm, but not sweat, because sweat will quickly turn to ice, and you want to layer up, but you don't want to look and feel like a marshmallow man. It's a damn near intractable problem, but Castelli's Elemento 2 7x(AIR) Men's Jacket offers up an elegant, slim-fitting solution.
It manages to balance weight, flexibility, breathability, and warmth, thanks primarily to Castelli's 7x(AIR) fabric. Quilted for warmth and naturally moisture wicking, 7x(AIR) traps heat against your skin while letting moisture move away, so you stay warm and dry even when conditions are at their toughest. To stop cold gusts from sapping your warmth, Castelli integrated WindShear wind-blocking inserts at the front, back, and triceps, and lined the body and collar of the Elemento with lightweight microfleece for extra insulation.
Materials are only half of the equation, though. Cut is also essential, and the Elemento has a slim, aerodynamically-minded fit that's not only fast but efficient, as it allows moisture to quickly transfer to the jacket's surface for easy evaporation while minimizing the space between your core and the insulation for additional warmth. It also moves with you, so you never feel restricted when stretched out on the bars for long winter base miles.
The articulated collar wraps comfortably around your neck in every position, and works with the raw-edge cuffs and dropped rear hem to seal out drafts without causing irritation. The Elemento also has three drop-in back pockets and reflective details for storage and visibility, respectively.