It's tough to find a decent jacket aimed at high output aerobic activities in cool to cold weather. It's even more difficult to find one that doesn't use synthetic insulation. Enter the Smartwool Propulsion 60 jacket.
Polartec's Alpha insulation gives manufacturers the ability to add warmth to really breathable layers. So far, we haven't seen anyone do it quite as well as the Outdoor Research Deviator Hoody. OR combines Polartec Alpha with Power Dry to keep you warm without getting soggy as the activity level ramps up.