The nearly weightless Castelli Aria Shell Jacket is a must for windy days. The windproof woven microfiber front blocks wind while the porous mesh side and shoulder panels keep you from overheating. In the Aria Jacket you stay dry and warm; yet as your body heats up, the circulating air will keep you at a healthy body temperature. The same breathable mesh on the sides and back of sleeves has enough of a stretch so the jacket fits like a second skin; wind won’t cause the jacket to flop around. The close to body design also eliminates cold air from seeping into the jacket. The collared neck and elastic at waist and wrists also seal out cold wind. The Aria Shell jacket keeps a cyclist warm in cool fall and spring weather. The one rear pocket is large enough to store GUs, bars or even an extra water bottle. The jacket is so compact that it can be easily folded into a small square and stored in your rear jersey pocket.