So light, and oh-so warm! The ATMOSPHERE was made for cold days on the mountain. This lightweight jacket has an RDS-certified duck down fill that will keep you warm in cold temperatures.The STORMLOCK shell provides double protection: it shuts out the wind and shrugs off light showers. The ATMOSPHERE is also extremely breathable, so it’s ideal for all kinds of winter sports, from X/C and downhill skiing to snowshoeing.If you get too warm, simply stash the jacket in its stuff sack and drop it in your pack.