Arc'teryx Atom LT Jacket - Men's This trim hybrid jacket is designed as an active-use insulation layer, providing vital core warmth with liberal mobility and breathability. Lightweight and compressible, the Atom LT Jacket features Coreloft(TM) insulation in the torso and arms. The side panels and underarms feature smooth faced, air permeable fleece stretch for ventilation. A wind and moisture resistant outer shell extends stand-alone usability. Features: ATOM - Versatile synthetic insulated mid layers with a high degree of weather resistance. LIGHTWEIGHT - High performance, minimalist design that is durable for its weight. ARC'TERYX ESSENTIALS - Versatile high performance designs for diverse activities and conditions. SYNTHETIC INSULATION - Man-made insulation with quick dry times, durability and retains warmth when damp.