Highlights
BEST USE: Ultralight Backpacking
PERFORMANCE: 2 Season
WEIGHT: 1lb 1.8oz | 505g
COMPRESSED VOLUME: 2.9 liters
COMFORT TEMP RATING: 35°F | 2°C
Shipping & Returns
Our warehouse is actively shipping orders from 8am to 1pm MST Monday through Friday. Most orders ship in one business day, but the transit time can take up to 7 days, depending on your distance from Boulder, Colorado.
2nd Day and Next Day Air orders will ship same day if placed by 1pm MST, Monday-Friday (except holidays).
All orders are eligible for fast and easy returns within 60 days of purchase.
For more details, please check out our Help Center
Find Locally
The EN Rating scale is a scientific test to determine the warmth of a sleeping bag. The test produces a Lower rating (for male sleepers) and a Comfort rating (for female sleepers). Both are listed in the features table on the product page.
A unisex sleeping bag with a Lower limit of 14ºF means a man should be comfortable down to air temperatures of 14ºF. The same bag will also have a Comfort limit, in the realm of 27°F, so a woman would be comfortable down to an air temperature of 27ºF. These ratings require a sleeping mat with an R-Value appropriate for expected ground temperatures – without this, the sleeping bag itself is unlikely to keep the sleeper warm enough.
A variety of factors impact sleeping bag warmth - the above temperatures are merely guidelines, not guarantees. It’s important to think of a sleeping bag, an appropriately insulating sleeping pad and a liner as a sleep system. For example - if you plan on sleeping in nighttime air temperatures of 27ºF / -3°C, choose a bag with a gender-appropriate rating of 23°F / -5°C, plus a sleeping mat with an R-Value of 2.5 to 3, and consider a Reactor thermal liner.


Description
The versatility of the Flame Ultralight Women's Sleeping Bag Series spans from an ultralight down-filled liner to a mid-winter fast-and-light sleeping bag. Each model uses premium materials and design to provide cutting-edge performance.
The women's specific mummy fit is narrower at the shoulder and wider at the hip, and features extra down compared to the unisex Spark models.
DESIGNED FOR WOMEN
Shaped for comfort
Narrower at the shoulders, wider between the hips and knees. Regardless of the position you sleep in (figure-four, on your side or on your stomach), this shape provides a significantly higher level of comfort by giving you the room to move without compressing the insulation.
Warmth from additional insulation
Additional insulation compared to unisex bags, positioned using different body mapping for thermal performance exactly where it is needed. Temperatures for Women’s sleeping bags are shown using the gender appropriate Comfort rating.
Maximum comfort for a good night's rest
Construction details like snug-fitting hoods and oversized draft tubes keep you warm in cooler weather. Super-soft fabrics are comfortable in any season.
You don’t have to narrow your options with a constrictive mummy bag – expand your horizons with a sleeping bag which fits the way you sleep.


Design Details
TECHNICAL FEATURES

The second highest-lofting down used in any of Sea to Summit’s sleeping bags or quilts. 850+ Fill Power indicates that one ounce (30g) of down will re-expand to over 850 cubic inches after compression. Higher loft means that less down can be used to achieve the same temperature rating – important for performance sleeping bags. The loft and down quality/composition are independently tested by the International Down and Feather Laboratory (IDFL) – a copy of the certification is supplied with every Sea to Summit sleeping bag. The down is responsibly sourced and RDS certified and treated with our non-PFC Ultra-Dry Down™ treatment.

Despite being incredibly lightweight, the 10 Denier UL Nylon is down-proof and surprisingly durable. A DWR finish helps to shed external moisture. This fabric is part of the secret to making the Spark and Flame Down Sleeping Bag Series some of the lightest, most packable sleeping bags available today.

100% of the down used in our sleeping bags and quilts is independently certified to the Responsible Down Standard (RDS). The RDS certifies down against animal welfare requirements and tracks it from the source to the final product. The purchase of RDS certified products demonstrates demand for better animal welfare practices in the down and feather supply chain. Sea to Summit is certified to the RDS. To learn more about RDS visit https://textileexchange.org/standards/responsible-down/

Sea to Summit sleeping bags do not contain PFCs.
Ultra-Dry Down™ uses a non-PFC hydrophobic treatment to ensure it absorbs less moisture and dries more quickly. The treatment does not affect the breathability or the lifespan of the down and lasts through at least 20 washings.
The down used in our sleeping bags is RDS-certified responsibly sourced.
Down and synthetic-insulated sleeping bags utilize a non-PFC DWR treatment on the shell fabric for external moisture repellency. This helps prevent the insulation from becoming damp if the sleeping bag comes into contact with condensation on a tent wall, for instance.

Sea to Summit Women’s Specific Sleeping Pads:
Built differently from the ground up, to provide women adventurers with the best possible sleep.
Both Air Sprung Cell and Self-Inflating mats have a shape that is narrower at the shoulder, then widest between the hips and knees to permit a natural side or ‘figure four’ sleeping position. Air Sprung Cell pads have more Thermolite® insulation than their Unisex counterparts. Self-Inflating pads have smaller-dimensioned Delta Cores in the hip and foot sections to create extra Comfort and Warmth Zones.
Sea to Summit Women’s Specific Sleeping Bags:
Engineered differently than Unisex models, to provide women adventurers with the best possible sleep.
They have a shape that is narrower at the shoulder, then widest between the hips and knees to permit a natural side or ‘figure four’ sleeping position. Women’s specific body mapping deploys insulation for warmth where it is most needed. Additionally, the Journey and Altitude down bags have a layer of Thermolite synthetic insulation in the footbox to warm your feet more quickly.
Journey, Altitude, and Venture can be zipped into many Sea to Summit Unisex sleeping bags.
Tech specs
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Best UseUltralight Backpacking, Bike packing, Bike Touring, Liner Bag
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Comes WithUltra-Sil™ compression bag and storage cell
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InsulationUltra-Dry Down 850+ Loft
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ShapeMummy
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Shell FabricUltralight 10D Nylon Shell
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Zip OptionsFlame 0-II: Right-side #3 YKK zipper; Flame III-IV: #5 YKK
48°F Regular | 48°F Long | 35°F Regular | 35°F Long | 25°F Regular | 25°F Long | 15°F Long | Liner Long | Liner Regular |
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Frequently Asked questions
Is this sleeping bag warm enough for cool-weather camping or travel?
Yes, this sleeping bag is great for cool-weather camping, especially the Flame 15°F or 25°F sleeping bag models. The 15°F will get you to early winter temperatures when paired with an insulated sleeping pad (3.5 R-Value or higher).
Can this sleeping bag be used as a liner in another sleeping bag?
Yes. You could use the Flame 55°F or Flame 48°F sleeping bags inside another bag to boost the thermal performance for cold-weather use. Tip: add one of these to a 20°F sleeping bag instead of buying a 0°F sleeping bag for occasional winter use.
Can this sleeping bag be zipped to another sleeping bag?
Yes - this sleeping bag can be zipped to a Spark sleeping bag with a full-length zipper.