This thing is awesome. Short writeup on my blog here!
Short and sweet: The Capilene Air Hoody is a 50% Polyester, 50% Wool “baselayer” that comes with or without a hood. They also make a pair of leggings, and its available in both mens and women’s fits. It’s a light, comfortable thin type fleece feeling layer that fits extremely well. It’s stretchy, breathes well, and the hooded version fits fantastically under a helmet. This layer wears comfortably with a tee-shirt underneath, or works well standalone. For highly aerobic activities like ski-touring or running, I’ll probably wear a 100% polyester shirt underneath, but for most days, it will be my go to baselayer, especially for activities involving helmets. Despite being marketed as just a baselayer by Patagonia, I really think of this piece more as a very light “fleece type” pullover, that is a lot more versatile than just a baselayer.