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Sea to Summit Altitude ATI

Altitude sleeping bag - ATI Womens.

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The opinion of Aventure Nordique

Offering the perfect backpacking balance of comfort vs weight, our Altitude Series sleeping bags have more space than traditional mummy bags, yet still provide the thermal efficiency you need when exploring above the tree-line.

The Free-Flow triple-zip design ensures your sleeping bag retains maximum warmth and efficiency when needed and multiple ventilation options when it’s not. The half zip on the left side of the bag provides freedom of movement for both arms, additional ventilation and also means the top third of the bag can be folded down as a mini quilt. The full length, two-way right side zip and separate foot zip transforms the bag into a full quilt for when the mercury climbs higher than expected.

If it’s warmth you’re after, close all the zips, pull the cord locks tight to drag everything in, and relax in luxurious comfort. The generous allocation of high quality 750+ Loft down ensures great insulation, while the oversized draft tubes prevents your body heat escaping. The panelled footbox and 3-dimensional hood make sure you’re not compressing the down when you’re trying to stay warm. The Altitude also features extra down overall and Thermolite panels under the foot area, to help keep heels and ankles warmer.

Vertical baffles over the chest section ensure the down insulation cannot migrate or shift to the outside of the bag during sleep, creating cold spots. A side block baffle construction maintains the 60/40 fill ratio, keeping more down on the top of the bag for maximum insulation.

Our tapered rectangular design gives you additional wriggle room inside the bag, perfect for a side or restless sleeper and an alternative if you find a traditional mummy shape too constricting. The women’s specific fit is wider at the hip and narrower at the shoulder and comes in two lengths.


  • Women’s specific tapered rectangular shape for perfect balance of space and adaptable warmth

  • Extra down overall and Thermolite panels under the foot area for additional warmth

  • Super-light 20D Nylon shell and lining fabrics for minimal packed size and maximum breathability

  • RDS 750+ Loft ULTRA-DRY Down for superior insulating power

  • Vertical chest baffles prevent down migration and cold spots

  • Free-Flow half left side, full length 2 way #5 YKK right side and separate foot zips for freedom of movement, increased ventilation and dual-use as a quilt

  • Oversized draft tube with anti-snag materials, prevents heat loss through zipper

  • Oversized neck draft tube with a dual adjustment system for even cinching and maximum warmth

  • Generously sized hood and dual cord adjustment for maximum warmth retention

  • Anatomically shaped footbox allows maximum down lofting, minimising heat loss from your feet

  • Large internal security pocket

  • Includes Ultra-Sil Compression Bag for compact storage

  • Zip Coupling: This bag is designed to pair with another

        Technical details

        Manufacturer Sea to Summit
        Product name Altitude ATI
        Article number DSLAT1
        Season 3 season
        Model Lady
        Fill Duck Down
        Cuin Ultra-Dry Down 750+ Loft 90/10
        Comfort rating -4°C
        Comfort Limit -10°C
        Extreme rating -29°C
        Dimensions Regular : max user height < 170cm
        Shoulders - Hips - Feet: Regular : 148/148/118 cm
        Folded size R : 6,5 L - L : 8,3 L
        Outer shell Nylon 20D
        Inner lining Nylon 20D
        Fill Weights R : 520 g / L : 580 g
        Weight R : 1080 g / L : 1170 g
        Colour Blue
        Country of Manufacture China


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