Versatile and very warm, the Thorium SV vest combines the exceptional insulation of a box walled down jacket with the freedom of a vest. Lofty 750 fill European grey goose down delivers superior warmth for little weight, is durably resilient, and packs easily. The vest's baffles use box wall construction to deliver maximum loft. The outer is soft, durable Arato 40 nylon, a lightweight material that withstands abrasion, packs compactly and has a DWR finish to repel moisture. The Thorium SV Vest is designed to deliver the versatility to perform as an outer layer in dry, moderately cold weather, or as a lofty midlayer for more severe temperature drops. Arc'teryx Down Composite Mapping technology combines the goose down insulation with panels of Coreloft synthetic insulation in areas prone to moisture. The Arc'teryx Athletic fit is streamlined enough to fit under a shell, but leaves room for layers underneath should it be worn as a standalone. The women's specific patterning and construction optimizes the Thorium SV's performance and fit. Gaskets are placed under the arms to block drafts, an internal dump pocket stows gloves or a toque, an internal zippered pocket secures a smartphone or wallet, and two insulated zippered pockets warm the hands.