Sea to Summit Spark SpI Sleeping Bag

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Packing down to the size of a 1-liter water bottle, this ultralight bag balances size, weight and warmth to make it an excellent choice for summertime backpacking, cycle touring and mountaineering.

  • Features

    • High-loft, premium 850-fill-power European goose down offers superb warmth with minimal weight; Ultra-Dry Down™ water-repellent treatment protects down from moisture
    • Ultra-Dry Down is a water-repellent polymer treatment applied to the down; Ultra-Dry Down retains 60% more loft and absorbs 30% less moisture than untreated down
    • With a European Norm (EN) lower-limit rating of 46°F, the Sea to Summit Spark SpI will help keep you warm on 3-season backpacking adventures in warm weather
    • You can also use the Spark Sp I as a booster bag by slipping it inside another sleeping bag to add warmth
    • Ultralight 10-denier Pertex® Quantum® fabric with a durable water repellent treatment sheds moisture
    • Soft 15-denier nylon fabric lines the sleeping bag for excellent comfort next to skin
    • Left-side 1/3-length zipper saves weight over a full-length zipper
    • Compresses to the size of a grapefruit


    Many sleeping bags are rated for temperature by an independent testing protocol. REI and the broader industry now use the International Organization for Standardization (ISO) 23537 protocol, which improves on the older European Norm (EN) 13537 standard; you may still see older items in our assortment that were only EN tested. With either protocol, each bag gets a Comfort (or T-Comfort) rating and Lower Limit (or T-Limit) rating. The Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Ratings are based on a person wearing one long underwear layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38. Many brands use the Comfort rating for women's bags and the Lower Limit rating for men's and unisex bags. Everyone's body and sleep comfort differ, and conditions of use (posture, clothing, sleeping pad R-value, wind, humidity, etc.) affect total insulation, so EN and ISO ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth.
    View all Sea to Summit Men's Sleeping Bags
  • Technical Specs

    Best Use



    Tested Lower Limit

    46 degrees (F) - EN

    Tested Comfort

    54 degrees (F) - EN

    Temperature Rating (F)

    46 degrees (F)

    Temperature Rating (C)

    8 degrees (C)




    Ripstop nylon

    Zipper Location


    Insulation Type


    Water-Resistant Down



    850-fill goose down



    Sleeping Bag Shape


    Stuff Sack Size

    4 x 9 inches

    Stuff Sack Volume

    2.5 liters

    Compressed Volume

    1.55 liters



  • Reviews
    10 reviews with an average rating of 4.3 out of 5 stars

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