Here's what other sites are saying:
the Mountainsmith Berthoud -20 sleeping bag features neck and zipper baffels and a relaxed mummy fit to keep you snug and sleeping well on sub-zero nights in the wild.
Whoever decided to camp in the middle of winter probably stays nice and toasty in Mountainsmith's Berthoud Sleeping Bag. This bag is undoubtedly Mountainsmith's warmest option in the Berthoud collection, and its synthetic insulation ensures warmth when snow seeps through the tent. Mountainsmith made the bag's shell out of snow-shedding materials, while the taffeta lining gives a soft feel. The Berthoud also features a form-fitting hood, multiple adjustments, a draft collar, and a tube that runs down the entire zipper to prevent cold drafts from waking you up in the middle of a ridiculously frigid night.
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