The North Face Aconcagua Jacket maps its insulation to where the body actually needs it. Two hundred grams of recycled polyester fill sit in the main body, dropping to 180 grams under the arms and along the sides where movement already generates heat, and easing to 60 grams in the draft flap. A WINDWALL fabric shell cuts wind before it reaches that insulation, and a non-PFC DWR finish sheds light rain and snow so the jacket holds up between an early hike and a walk across town. What Our Gearhead(R) Experts Are Saying:"I've worn this on a cold morning hike and then straight into a full day of errands without once feeling like I needed to peel a layer off. The underarm panels are noticeably thinner than the body, and that's exactly where I never want extra bulk."