- Fold-Down Second Zipper Provides added Ventilation and Easy Access, Main Zipper Anti-Snag Slider reduces Snagging
- Anatomical Wrap-Around Footbox Increases Insulation and Room for Your Feet, More Warmth and Comfort
- Certified 650-Fill-Power Down with Down Defender to Improve Water-Resistance in Wet Conditions
- Nautilus Multi-Baffle Hood
- Down-filled Collar with Easy Access Draw Cord
- Full Length Locking YKK Two Way Zipper with Draft Tube to Reduce Heat Loss
- Internal Stash Pocket and Heater Pocket in Footbox
Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.
Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
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