Sea To Summit Alpine Down Winter Sleeping Bag -40°F

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The Alpine down mummy sleeping bag is designed for the rarefied world of high-altitude and arctic conditions. It features cutting-edge materials, the highest quality Ultra-Dry down, and complex construction. Expedition mummy sizing allows you to wear extra clothing, and boot liners inside the bag.

If you are going above or beyond, the Alpine is the bag you will want to take with you.


  • ULTRA-DRY Down 850+ Loft 90% Down Cluster Premium Goose Down certified Responsible Down Standard (RDS)
  • Free-flow zipper system: one full-length YKK® #5 main zip and a half-length zip on the opposite side for ventilation
  • Expedition sizing gives you room to wear extra clothing inside the bag
  • Anatomically-shaped, oversized foot box can accommodate boot liners
  • Technical shaped hood with hidden drawcords for maximum insulation
  • An oversized draft collar which fits snugly around your shoulders
  • Internal pocket for phone / GPS / valuables
  • Includes lightweight Ultra-Sil compression bag and storage cell

Tech Specs:

-40°F Regular -40°F Long
Bag Weight 4 lbs 2 oz 4 lbs 10 oz
Compressed Vol 14.7 L 19.5 L
Compressed Sack XL - 30L to 10L XL - 30L to 10L
Fill Weight 44 oz 55 oz
Fits up to Height 6 ft 6 ft 4 in
Season Rating 4 Season 4 Season
Temperature Rating -40ºF -40ºF