Alpine-ready and proven across a range of alpine and backcountry trips the Arc'teryx Cerium Men's Jacket packs down small to fit efficiently into your pack, weighs little, and delivers, when unfurled big warmth when you need it. Refined for optimal fit and efficiency this uses 850 fill responsibly sourced down throughout all but the areas prone to moisture, where Coreloft™ synthetic insulates even if damp and moves vapor quickly. The recycled 15D Arato™ nylon outer is light and durable, and a bio-derived liner made from 60% castor bean oil to reduces petroleum use. This is a piece you can feel good about that delivers as a warm midlayer that glides comfortably under a shell with room for layering underneath, keeps you comfortably warm in cool weather when you want weightless warmth that won’t slow you down, and comes with its own stuff sack for easy transport, whether you’re stuffing it into your carry-on or packing it into your day pack.