COMPETITION: WINNER - Win a Mountain Equipment Firefly Sleeping Bag

WINNER: Luluazul

The Firefly is the lightest, most efficient bag we have ever developed. If you want reliable warmth for minimum weight, look no further. The advanced design which features our 7-baffle anatomically shaped hood and four-baffle foot-box coupled with ultralight 10 denier fabric throughout have helped open up a new standard in superlight bag construction.


By utilizing slanted box-wall baffles throughout the entire main body, meaningful weight is removed from the bag's structure. On the inside of the bag the conventional neck collar is replaced by a significantly lighter collar baffle (which also allows higher concentrations of down to be placed within the main body of the bag) and EXL® has been added to the top half of the bag to minimize dead air space, reduce drafts and pull fabric away from the down to maximize loft.

Firefly Specs

Firefly Specs

Firefly Spec


One of the lightest downproof fabrics on the planet. Perfect for alpinists and backpackers for whom weight is absolutely critical. Despite being just 26g/m2, the fabric has exceptional tear resistance, giving you peace of mind on longer or more remote trips.

Firefly  © Mountain Equipment

Neck Baffle

Specifically designed for Extreme Light models, a significantly lighter yet highly thermally efficient replacement for the conventional neck collar. Used in conjunction with our Gemini™ zip baffle.


Our Good Night's Sleep Guarantee

Good Night Sleep Guaranteed In addition to these Standard temperature ratings we also offer our Good Night's Sleep temperature rating. This is a rating which we feel is the most accurate reflection of a bag's potential in real-life situations. In most cases our Good Night's Sleep rating will tally closely to that of the EN/ISO result, but for certain bags the discrepancy might be greater.

This is because the EN test is strongly affected by certain aspects of a bag's makeup which don't make as much difference in real life, such as the face fabric and the shape of the bag. Our Good Night's Sleep rating is guaranteed and is based on extensive experience of manufacturing sleeping bags and extremely exhaustive testing in the laboratory, during cold chamber testing, and is influenced by user feedback from countless expeditions stretching back more than fifty years.

We suggest you base your sleeping bag purchase most closely on the Good Night's Sleep temperature rating, but of course if you think you particularly feel the cold or otherwise, then you should take this into consideration.


  • Plasma™ 10D outer shell is incredibly light and exceptionally breathable
  • 274g of 90-10 Russian Goose Down with a minimum fill power of 800
  • Alpine fit with EXL® system improves loft and maximises thermal efficiency
  • Slanted box-wall baffles throughout
  • Ground level side seams
  • 7 baffle low volume anatomically shaped hood
  • 4 baffle anatomically shaped and offset foot-box
  • Full length Gemini™ zip baffle
  • Plasma™ 10D inner throughout
  • Supplied with waterproof roll-top stuff-sack and storage cube
  • Good Night's Sleep Temperature: -1°C/30°F
  • Comfort: 4°C/39°F
  • Comfort Limit: -1°C/30°F
  • Extreme: -16°C/3°F
  • Total Weight: 560g / 20oz
  • Fill Weight: 274g / 10oz
  • Pack Size: 25cm x 19cm x 16cm

Visit our Sleeping Bag Buying Guide for more detailed information.

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