Warmest, thermo-mapped Atom for cold, mid-output mountain activities. This product was previously the Atom Heavyweight Jacket.When warmth is your priority, zip up the Atom SV Jacket. Made for frigid hikes and above-the-treeline adventures, its synthetic insulation seals in heat for consistent comfort in cold, damp, and windy conditions. Strategically placed for max breathability, full-length stretch side panels provide a welcome flow of air on that final summit stretch. The workhorse in your winter kit, the Atom SV delivers hefty protection on its own and rides comfortably under a hardshell when the sky opens up. What's been updated: Updated with a more streamlined fit and a FC0 DWR (Durable Water Repellent) finish that’s free from intentionally added PFAS. Improved male-specific thermal patterning on the side panels maximizes breathability and reduces overheating.