The Atom SL Vest offers minimalist insulation for warmer days or higher output activities. The Tyono™ 20 shell is lightweight, durable and wind resistant, and the Coreloft™ Compact insulation is compressible, dries quickly, and allows airflow. Lightweight air-permeable fleece side panels provide ventilation and thermal performance. Composite Mapping is used to place materials and insulation types in the areas that will provide maximum benefit.