Arc'teryx Atom LT Pant Men's ATOM LT PANT - These Coreloft insulated pants are designed to keep you warm on the coldest days, or to be used as an extra outer layer during low activity moments in the mountains. ARC'ESSENTIALS - Versatile high performance designs for diverse activities and conditions. ATOM - Versatile synthetic insulated mid layers with a high degree of weather resistance. LIGHTWEIGHT - High performance, minimalist design that is durable for its weight. SYNTHETIC INSULATION - Man-made insulation with quick dry times, durability and retains warmth when damp.