Mountain Equipment Helium 400 Sleeping Bag (-5°C/23°F)

An incredibly light, versatile and packable sleeping bag that is well suited to backpacking, mountaineering and cycle touring. The Helium 400 will happily cope with cooler nights during the spring and summer months.

Using 403 g 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 will not 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.

Key Features

Insulation

• Insulation optimised baffle-by-baffle for maximum warmth-to-weight ratio
• Regular: 403 g of 90/10 duck down with 700+ fill power
• Long: 425 g of 90/10 duck down with 700+ fill power
• Ethically sourced through DOWN CODEX and RDS 3.0
• Each bag includes a unique DOWN CODEX code for transparency on sourcing and fill power

Materials

• Recycled Helium 20D outer: 38 gsm lightweight recycled 20-denier fabric, windproof with PFAS-free DWR
• Supersoft 20D lining: 38 gsm recycled downproof nylon, breathable and soft against the skin with PFAS-free DWR

Patterning and Design

• Alpine 2.0 fit, a refined tapered shape that optimises thermal efficiency while keeping weight low
• Slanted box-wall baffles reduce structural weight while optimising insulation
• Strategic fill distribution with high-density fill in key areas including the underside, hood and foot box

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 and Closures

• Gemini full-length entry zip baffle practically eliminates heat loss and is stiffened to prevent snagging
• Lode Lock magnetic closure system for secure, one-handed use in the dark
• Integrated adjustable down-filled neck collar for additional warmth retention

Packed and Storage

• Supplied with a waterproof roll-top stuff sack
• Includes a storage cube to preserve down loft during long-term storage at home

Specifications

Ideal For

• Backpacking and trekking in spring, summer and early autumn
• Mountaineering and cycle touring requiring a lightweight, packable sleeping bag
• Travel to more northerly latitudes or higher altitudes where cooler nights are expected

Care Instructions

Technology

	Down 700 Mountain Equipment's 700 fill power duck down sits in the sweet spot of price and performance, offering excellent quality for all but the most serious use. Being down, it has a superb warmth-to-weight ratio, compressibility, lifespan and softness.
	DOWN CODEX Since 2009, Mountain Equipment's DOWN CODEX programme has set high ethical standards for down sourcing, eliminating live-plucking and force-feeding, and ensuring only top-quality virgin down is used, certified to the Responsible Down Standard (RDS).
	Helium 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 low weight.
	Fair Wear Mountain Equipment is a proud member of the Fair Wear Foundation, committed to implementing the highest standards of working conditions in garment production. Designed and developed in the UK.