Skip to content
    Search 0
    ME-005968

    Helium 400

    Regular price $419.95
    An incredibly light, versatile and packable sleeping bag that's well suited to backpacking, mountaineering and cycle touring. The Helium 400 will happily cope with cooler nights during the spring and summer months.
    • Ideal for: Backpacking & Trekking
    • Weight: 820g/1 lbs 12.9ozs
    • Thermometer
      Good Night's Sleep Temperature: -5°C/23°F
    Select Colour ME-01635 Majolica Blue
    Size
    • Free UK mainland delivery on orders over £50
    • Hassle free returns within 30 days.

    Helium 400

    Using 403g of minimum 700-fill power DOWN CODEX-approved duck down and a high-performance, 100% recycled Helium 20D outer fabric, the Helium 400 is warm, lightweight and ultra-compressible for easy packing. Efficiently sized, supremely comfortable and very low in weight for backpacking and cycle touring while still being warm enough to cope with chilly nights.

    Using 403g of minimum 700-fill power DOWN CODEX-approved duck down and a high-performance, 100% recycled Helium 20D outer fabric, the Helium 400 is warm, lightweight and ultra-compressible for easy packing. Efficiently sized, supremely comfortable and very low in weight for backpacking and cycle touring while still being warm enough to cope with chilly nights.

    Slant-baffle construction through the body maximises warmth, improves packability, and prevents down migration, keeping you warm night after night and preventing cold spots. At the foot of the bag, a four-baffle system focuses essential warmth around your feet, while in the hood, a five-baffle system optimises comfort and keeps the down precisely where it needs to be.

    Inside the bag, a 100% recycled Supersoft 20D lining fabric with PFAS-free DWR offers breathability and durability for comfortable nights and a long lifespan, while a full-length Gemini™ entry zip baffle practically eliminates heat loss in this vulnerable area and is stiffened so it won’t catch in the zip. The low-profile magnetic Lode Lock™ closure and collar drawcords are practical and easy to use in the dark.

    Designed with a technical yet comfortable Alpine 2.0 fit, Helium bags optimise thermal performance while minimising weight. With a Good Night’s Sleep Temperature of -5°C (23°F), the Helium 400 offers reliable warmth for travel to more northerly latitudes and for early spring and autumn use at higher altitudes.

    Performance & Specification

    User Size:

    • Regular: 185cm (6 ft 1 in) maximum user height
    • Long: 200cm (6 ft 6 in) maximum user height

    Weight:

    • Regular: 820g (1lb 12.9oz)
    • Long: 870g (1lb 11.5oz)

    Insulation:

    • Duck Down is ethically sourced via DOWN CODEX© and RDS 3.0.
    • Regular: 403g of 90/10 Duck Down with 700+ fill power.
    • Long: 425g of 90/10 Duck Down with 700+ fill power.

    Temperature Ratings (EN13537/ISO23537):

    • Comfort: 0°C (32°F)
    • Comfort Limit: -6°C (21°F)
    • Extreme: -24°C (-11°F)

    Learn more about EN ratings

    Good Night's Sleep Temperature:

    • -5°C (23°F)

    Learn more about GNSG

    Packed Size:

    • 24cm x 21cm x 20cm (9.4in x 8.3in x 7.9in)

    Manufactured in:

    • Vietnam

    Features

    Insulation:

    • Optimised baffle-by-baffle for maximum warmth-to-weight ratio.
    • Regular: 367g of 90/10 Duck Down with 700+ fill power.
    • Long: 388g of 90/10 Duck Down with 700+ fill power.
    • Ethically sourced through DOWN CODEX© and RDS 3.0. Learn more about DOWN CODEX
    • Each bag includes a unique DOWN CODEX© code for transparency on sourcing and fill power.

    Materials:

    • Recycled HELIUM™ 20D: A lightweight (38gsm), recycled 20-denier fabric that balances durability, compressibility, and weather resistance. Densely woven for wind and heat loss resistance with a PFAS-free DWR finish.
    • Supersoft™ Lining: 38gsm 20D recycled downproof nylon for breathability, durability, and next-to-skin comfort. PFAS-free DWR finish.

    Patterning & Design:

    • Designed for long-term durability and high performance.
    • Women’s Alpine Fit: A refined, tapered shape with a zoned EXL® system that improves thermal efficiency while keeping the weight low.
    • Slanted box-wall baffles: Reduce structural weight while optimising insulation.
    • Strategic fill distribution: High-density fill in key areas (underside, hood, foot box) to prevent down migration and enhance warmth.

    Foot box:

    • Trapezium 4 System: A four-baffle design that enhances warmth and prevents compression around the feet.

    Hood:

    • Five-baffle construction for precise down control, low weight, and superior insulation.
    • Spacious yet snug with dual tether drawcords to minimise heat loss.

    Zip Baffles & Collars:

    • Gemini™ Baffle System: A lightweight, low-profile design that minimises heat loss while maintaining protection.
    • Lode Lock™ System: A secure, magnetic fastener with a mechanical lock for a one-handed quick-release closure.
    • Integrated, adjustable down-filled neck collar for extra warmth.

    Additional Features:

    • Waterproof roll-top stuff sack: Maximises pack space and keeps gear dry.
    • Storage Cube: Preserves down loft for better long-term performance. Ideal for at-home storage.

    Good Night’s Sleep Guaranteed

    Every Mountain Equipment sleeping bag carries our exclusive Good Night's Sleep Guaranteed temperature rating.

    This rating is based on lab testing, real-world trials, and expedition feedback, ensuring comfort for experienced users at the stated minimum temperature.

    If your bag is not as warm as expected, we will upgrade you to a warmer model, giving you peace of mind.

    Learn more

    Our Guarantee

    We fully guarantee our products against defects in materials, components, and craftsmanship for their reasonable lifespan.

    If a defect occurs before or during use, we will repair or replace the item at our discretion.

    Learn more

    Care

    General Care:

    • Spot clean with a damp, soapy cloth. Avoid full washes unless necessary.
    • Keep zippers clean and lubricated for smooth operation.

    Washing:

    Drying:

    • Ensure the bag is fully dry before storage. Follow our care guide for best practices.

    Storage:

    • Avoid long-term storage in the waterproof stuff sack.
    • Store uncompressed in a cool, dry place, ideally in the provided storage cube or a large container to maintain loft.
    • Good Night's Sleep Guarantee
      Our “Good Night’s Sleep Guarantee” allows you to purchase a new sleeping bag with confidence. We’re so confident in our “Good N...

      Our “Good Night’s Sleep Guarantee” allows you to purchase a new sleeping bag with confidence. We’re so confident in our “Good Night’s Sleep Temperature” rating that if you decide your new sleeping bag isn’t quite warm enough, we’ll upgrade your bag to one with a warmer specification

    • DOWN CODEX®
      The DOWN CODEX® is our multi-award-winning certification scheme that considers the environmental, ethical and animal welfare ma...

      The DOWN CODEX® is our multi-award-winning certification scheme that considers the environmental, ethical and animal welfare matters relating to our down supply chains. Underpinned by the Responsible Down Standard, it is based on independent audits and a rigorous paper trail.

    • Helium
      Helium fabrics are exceptionally light, compressible and soft. Their densely woven construction ensures the highest levels of d...

      Helium fabrics are exceptionally light, compressible and soft. Their densely woven construction ensures the highest levels of down-proofing, fibre resistance, and wind resistance, ensuring lasting performance despite their extremely light weight.

    • Down 700
      Our 700 fill power down duck is in the sweet spot of price and performance, offering excellent quality for all but the most ser...

      Our 700 fill power down duck is in the sweet spot of price and performance, offering excellent quality for all but the most serious use. Being down, it has superb warmth-to-weight ratio, compressibility, lifespan, and softness.
    Important California Resident Info

    Trace your down

    What is the DOWN CODEX code?

    Click here to get a demo code and trace