Performing as midlayer and standalone across a broad range of activities and output levels, the iconic Atom 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, and stretch fleece side panels improve ventilation and freedom of movement. The Atom Jacket was previously the Atom LT Jacket. Size and Fit Tips: Fitted Fit - This trimmer fit is patterned to stay close to the body through the chest, waist, hip, and thigh. Its low profile eliminates bulk, moves with the body, and fits comfortably over our first layers. This model's fit has evolved. Technical Features Wind resistant Moisture-resistant outer face fabric Breathable Lightweight Compressible and packable Insulated Collar Configuration Mid-height collar is insulated and fleece-lined, layers well Construction Performance stretch fleece side panels give ventilation Resilient Coreloft™ Compact 60 insulation retains loft Light, soft Tyono™ 20 is air permeable Cuff & Sleeves Configuration Stretch-knit cuffs Cuff construction increases durability, eases layering and removal Design & Fit Trim fit for base layer or light mid-layer use Fabric Treatment DWR (Durable Water Repellent) finish repels moisture Hem Configuration Dual lower hem adjusters Drop back hem Laminated hem Pocket Configuration Two hand pockets with hidden zippers Internal chest pocket with zip Sustainability Contains materials that meet the bluesign® criteria Dope dyed lining fabric Zippers & Fly Configuration No Slip Zip™ front zipper Custom TPU zipper pulls