Arc'teryx Atom LT Jacket - Women's 2012: Ideal for ambitious days when the mercury plummets, the Arc’Teryx Atom LT Jacket warm mid-layer features composite materials that provide balanced warmth and breathability. The arms and torso are fortified with Coreloft™ insulation, and the side panels and underarms incorporate Polartec® Power Stretch® with Hardface® Technology to increase mobility and breathability. A wind and moisture resistant outer shell extends stand-alone usability.