Performing as a midlayer and standalone across a broad range of activities and output levels, the iconic Atom LT is an Arcteryx mainstay. Over time, the design has been refined to elevate performance, improve durability and extend versatility. The 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, and stretch fleece side panels improve ventilation and freedom of movement.