A go-to for serious cold, The Thorium's the one you reach for when you need the warmth of down to keep you comfortable outside. Created for efficient performance, comfort, and durability, it's filled with warm, lofty responsibly-sourced 750 fill-power grey goose down and has a lightweight, abrasion-resistant Arato 30 nylon shell. Down Composite Mapping strategically places Coreloft synthetic insulation in areas prone to moisture, a bio-derived liner reduces petroleum use, a DWR treatment repels water, and multiple pockets provide storage.