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L.L.Bean Ultralight Sleeping Bag, 0 Mummy

LL Bean's Ultralight 0 Degree Mummy Bag features Cross-Core technology, testing the boundaries of Aerogel and PrimaLoft Gold insulation. Theoretically, this design should increase the sleeping bag warmth-to-weight ratio.


  • More lightweight that I was expecting.
  • One of the more cost-effective sleeping bags I've seen.
  • LL Bean's customer service is awesome.


  • Pack-ability: despite its special PrimaLoft Technology this bag takes up A LOT of space.
  • It's not as warm as other 0 degree bags I've tested.

Finding the right sleeping bag can prove to be challenging. Features like sleeping bag loft, temperature rating, and weight can test even the most experienced backpackers. But LL Bean's 0 Degree Ultralight Sleeping Bag does a good job of implementing the outdoor industry's most innovative materials to make it a force with which to be reckoned. Combining a NASA material with PrimaLoft Gold Insulation, the 0 Degree Ultralight Sleeping bag adds warmth without compromising weight-efficiency.

Initial Observations: Weighing a surprising 2lbs 15oz, LL Bean's 0 Degree Ultralight Sleeping Bag is surprisingly lightweight for a 0-degree sleeping bag. Competitive products typically weigh somewhere between three and four pounds (unless you can afford really expensive sleeping bags, in which case they can get pretty lightweight). 

MSRP: $299 Regular / $309 Long

Weight: 2lb 15oz

Limitations: Regular fits 6' / Long fits 6'6

Suggested Use: Camping / Casual Backpacking


  • Durable
  • Small inside pocket
  • Half-length zipper
  • Free shipping

Backcountry Testing: I took this sleeping bag out for a number of trips in Colorado’s backcountry. Temperatures varied from low 30s to mid 40s. When the temperatures sank to the low side, my toes were noticeably chilly. I'd like to see additional loft in the toe box area of this sleeping bag. 

A 0-degree temperature rating generally means that you'll survive 0 degree temperatures, but you'll only be comfortable in 15 degree or warmer temperatures. So, to be fair, the 0 Degree Mummy Bag isn't really intended to take on 0 degrees with pizzaz. But it should perform well in the 30s. If the toe box had additional insulation, I think it would perform significantly better.

Additionally, the 0 Degree Mummy bag is a Unisex product. A lot of companies incorporate male and female temperature ratings, because females tend to need warmer products. I often carry a 0-degree sleeping bag when I'm expecting overnight temperatures to be in the 40s. It'd be nice to see male vs. female temperature ratings on the homepage for this product. 

What do other reviewers think?

According to Gear Junkie, “Originally developed by NASA, silica aerogel is a highly porous, low-density structure that blocks heat and cold like nothing else. But it has some serious limitations. It does not breathe, and it cannot get wet or will break down.”

Additionally, “L.L. Bean claims that the mid-loft ultralight insulation “retains much of its insulating ability even when compressed.” This departs from most insulations, particularly down, that lose insulating properties when compressed.”

What I found:

While it seems that the innovative materials could substantially alter LL Bean's line of sleeping bags in the backpacking world, they won't come without drawbacks, according to Gear Junkie. I actually didn't find the breathability to be less than average in this sleeping bag. And as a rule of thumb, backpackers should always aim to keep their sleeping bags dry, regardless of the sleeping bag materials.

The idea of retaining heat while compressed is incredibly alluring. Overall, I found this to be true as well. This could mean that even after substantial use, the 0 Degree Mummy Bag should retain it's temperature rating. 

Conclusions: While the prospect of implementing silica aerogel into outdoor gear is exciting, I wasn't exceedingly impressed with the warmth-retention of this sleeping bag for my personal use. This sleeping bag performs well in high 30s, but I'm not sure it'd provide enough warmth for my use below the 30 degree mark. I would definitely use this sleeping bag in warmer temperatures, but I'm not convinced it would work for me in chilly temperatures. Overall, I found this product to be impressive in it's durability, it's weight and the cost, making it a viable option for the right person.

Disclaimer: This product was donated for the purpose of this review. But the generosity in no way shapes my objectivity.

Source: tested or reviewed it for the manufacturer (Kept it)

The author of this review received a sample of the product from the brand or its representative in exchange for a review.

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Price MSRP: $299.00
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