This is my favorite winter jacket and I have a lot of 'em. Here in the Eastern Sierra it is high, dry and cold, by which I mean in the low thirties (fahrenheit!). This jacket was made for such conditions, the Alpha direct insulation and advanced breathable shell make for a comfortably dry and therefore warm ride. It's not actually a substitute for its predecessor, the Alpha Doppio, which I also have, because this jacket is stretchy and fits tight, which limits layering. The Doppio is (much) more weather proof and has room for more layers, so I save it for the stormy days. Finally, the caveat is, this jacket is not perfectly windproof despite what the ad copy says. It takes a very cold day with a headwind, but I have to break out the shell. I have that with me anyway, because as Castelli admits, this is a fair weather jacket...
