Performing as midlayer and standalone across a broad range of activities and output levels, the iconic Atom LT is an Arc'teryx mainstay. Over time, they have refined the design to elevate performance, improve durability and extend its versatility. Its Coreloft Compact insulation retains heat when wet and withstands repeated packing and unpacking. Light, soft and durable, the Tyono 20 face fabric resists wind and weather, while stretch fleece side panels improve ventilation and freedom of movement.