REI Co-op Zephyr 20 Sleeping Bag - Women's

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Warm enough for backpacking spring through fall, the women's REI Co-op Zephyr 20 sleeping bag is our top synthetic design—light, compressible and cozy, with construction that maximizes comfort.

  • Features

    • With an International Organization for Standardization (ISO) T-Comfort rating of 22°F and T-Limit rating of 9°F, this bag is suitable for 3-season use
    • Women-specific design offers more room in hips and slightly narrower shoulder girth for the best fit and thermal efficiency
    • Synthetic polyester insulation is durable and highly compressible; the fill also retains some insulating ability if it gets wet
    • Shingle construction with overlapping layers distributes insulation evenly and prevents cold spots
    • Mummy shape is thermally efficient, yet roomy enough from shoulder to knee to ensure sleeping comfort
    • Trapezoidal footbox gives room to wiggle toes and the baffle in the toe box holds extra insulation in place to help keep feet warm
    • Hood, insulated muffler and full-length zipper draft tube keep warmth in and cold out
    • New zipper cover and internal antisnag strip combine for easy zipping
    • Stash pocket under collar holds small essentials
    • Differentiated drawcords allow quick hood and neck adjustments in the dark
    • Ripstop polyester shell offers durability with abrasion- and tear-resistance for years of use
    • Nylon stuff sack and polyester storage bag are included


    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 REI Co-op Women's Sleeping Bags
  • Technical Specs

    Best Use


    Tested Lower Limit

    9 degrees (F) - ISO

    Tested Comfort

    22 degrees (F) - ISO

    Temperature Rating (F)

    20 degrees (F)

    Temperature Rating (C)

    -6 degrees (C)


    Ripstop polyester (bluesign® approved)

    Zipper Location


    Insulation Type



    Polyester fibers


    Nylon taffeta (bluesign® approved)

    Sleeping Bag Shape


    Stuff Sack Size

    7.25 x 16.5 inches

    Stuff Sack Volume

    10 liters




    Contains materials that meet the bluesign® criteria

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