The Castelli Squall Shell Jacket is a perfect, lightweight, and packable jacket designed to keep you dry in case of a rain shower or to take the chill off during mountain descents. It is fully waterproof and windproof on the front and back for comfort in unpredictable weather. Its lightweight, highly packable design makes it easy to stash in a jersey pocket. The jacket features taped seams, a waterproof membrane, and reflective stripe on the back for high visibility in low light conditions. It has a high collar and elastic at the waist and wrists to keep out water and cold air. Ideal temperature range: 4 – 18 C / 39 – 64 F. Weight: 3.3 ounces. This jacket is made to take with you on days when it looks like rain, but its lightweight and packable nature means you can take it on every ride just in case.