Arc'teryx Cerium LT Vest - Men's A minimalist down vest providing a high level of core warmth for very little weight, the Cerium LT performs as a midlayer or standalone in cool, dry conditions. Premium 850 fill down is resilient and warm, the Arato(TM) 10 shell provides lightweight durability, and Down Composite Mapping(TM) strategically places Coreloft(TM) synthetic insulation in moisture-prone areas. The trim fit layers easily under a shell, and the sewn-through construction further reduces weight and increases packability. CERIUM Streamlined, minimalist and lightweight technical down insulation. High warmth to weight ratio. LIGHTWEIGHT High performance, minimalist design that is durable for its weight. ARC'TERYX ESSENTIALS Versatile high performance designs for diverse activities and conditions. DOWN INSULATION Highly efficient natural insulation that compacts well and offers excellent warmth to weight.