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Cumulus Alaska 900

Zip Side

The Cumulus Alaska 900 is a lightweight down sleeping bag built to perform in cold conditions.

With a light Pertex Quantum shell combined with 900g of 700 cuin Polish goose down, this quality sleeping bag plugs the gap between fast and light alpine mountaineering bags and heftier expedition bags. With a total weight of 1370g it is one of the lightest sleeping bags in its class. 

Who are Cumulus?

Designed and built in Poland, Cumulus draw on 30 years of experience and know-how in down and textile manufacture to provide some of THE best sleeping bags on the market. At the vanguard of sleeping bag construction techniques and design innovation, Cumulus offer as many as five methods of chamber construction, each developed to offer its own unique benefits [Cumulus Down Sleeping Bag Construction article]. All bags use sustainably sourced Polish goose or duck down, high-grade face and liner fabrics from Pertex, YKK zippers and, unlike most other sleeping bag brands, are entirely constructed in the EU.

Cumulus clothing and sleeping bags hold the EDFA (European Down and Feather Association) certificate for ethical down sourcing.

Advice on Temperature Ratings

Temperature ratings are used to indicate a bags performance and help you decide between models. However, they are subjective and can be greatly affected by factors such as what you're happy to wear (clothing wise) in conjunction with the bag, your health and metabolism, how much you have had to eat or drink, humidity and altitude, the type of shelter used and whether you are using a suitable insulating mat.

As a guide, the "Comfort" rating indicates the range at which a woman gets a comfortable night’s sleep, the "Limit of Comfort" rating indicates the range at which a man gets a comfortable night’s sleep and the "Extreme" rating indicates a range at which a woman is protected from hypothermia. The Extreme rating is basically a survival rating and it is not advisable to rely on this for general use.

More Help? For further assistance on choosing your down sleeping bag, please view this article explaining fill power, the pros and cons of down over synthetic insulation and more info on caring for your bag available to view here: A Guide to Down Sleeping Bags.


  • Fabric: Pertex Quantum, 35 g/m²
  • Filling: Polish goose down, 700 cuin
  • Construction: “V” chambers
  • Independently filled top and bottom of the sleeping bag
  • 175 cm YKK separating zip with two self-locking sliders
  • Can be opened and ventilated at the bottom of the sleeping bag
  • Can be combined with other sleeping bags
  • 2 full length, down-filled, zip insulating baffles
  • Independent down-filled collar
  • Three-dimensional, elastic adjustable hood fitted with stopper
  • Internal pocket
  • Additional, large mesh bag to store your sleeping bag at home


        • Total weight: 1370 g
        • Down weight: 900 g
        • Weight of unfilled sleeping bag: 470 g
        • Comfort temperature: -10 ˚C
        • Limit temperature: -18 ˚C
        • Extreme temperature: -39 ˚C
        • Maximum user height: 190 cm
        • Length: 210 cm
        • Width (top/bottom): 85/59 cm
        • Stuffsack’s dimensions (height/diameter): 32/21 cm
        • Stuffsack’s volume: 11.1 l
        • Number of down chambers: 37

              10 Year Warranty
              Made in the E.U.

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