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

A lightweight, adaptable, and easily packable sleeping bag, crafted with extra space to enhance comfort. It presents an excellent option for those embarking on backpacking adventures or extended travels through summer or cooler spring evenings.

Featuring a roomier design than the standard Helium models, the Helium GT range has been developed with prolonged use in mind, offering outstanding comfort for individuals who prefer more freedom of movement. The Helium GT 400 utilises 449g of duck down with a minimum 700 fill power, all certified under the DOWN CODEX standard, paired with a durable and high-performance Helium 20D outer fabric made entirely from recycled materials. This sleeping bag achieves an ideal balance of weight and warmth, making it a reliable choice for both backpackers and cycle tourers seeking comfort during brisk nights.

The body of the bag incorporates slant-baffle construction, which enhances thermal efficiency, aids in compressibility, and effectively prevents the down from shifting—ensuring consistent insulation and avoiding cold spots. At the foot end, a four-baffle structure provides concentrated warmth where it’s most needed, while a five-baffle system in the hood ensures the down stays in place, delivering optimum comfort around the head and neck.

The interior is lined with a Supersoft 20D fabric made from 100% recycled fibres and treated with a PFAS-free DWR, which offers excellent breathability and long-lasting durability. A full-length Gemini™ zip baffle significantly reduces heat loss along the side entry, and it features a stiffened design to prevent the fabric from snagging. The Lode Lock™ magnetic closure, paired with practical collar drawcords, is designed to be intuitive and fuss-free, even in the dark.

Shaped with a more generous GT Fit, the Helium GT maintains the same tapered silhouette as the Alpine fit but with added width that enhances comfort without compromising performance. With a Good Night’s Sleep Temperature rating of -5°C (23°F), the Helium GT 400 delivers dependable warmth for longer journeys and seasonal travel from spring into the heart of summer.

Features

• The sleeping bag is filled with 449g of DOWN CODEX-certified duck down with a minimum fill power of 700.
• Its Helium 20D outer fabric is made entirely from recycled fibres, combining performance with sustainability.
  
• The Supersoft 20D lining, also 100% recycled and PFAS-free, provides breathability and comfort throughout the night.
• Slant-baffle construction across the body enhances warmth and prevents the down from shifting.
• A four-baffle system in the footbox concentrates warmth precisely where it is needed most.
• The hood benefits from a five-baffle construction that maintains insulation and shape.
• A full-length Gemini™ zip baffle reduces heat loss and is designed not to snag during use.
• The low-profile magnetic Lode Lock™ closure offers simple and secure fastening, even in darkness.
• Collar drawcords add another layer of thermal control and are easy to adjust at night.
• The GT Fit mirrors the Alpine fit’s shape while offering more space for comfort over extended use.
• The sleeping bag offers a Good Night’s Sleep Temperature of -5°C, making it suitable for spring and summer travel.
  
  

Specifications

Technology

	Down CODEX® Since 2009, our 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).
	Down 700 Down is the finest insulator. Manmade insulations cannot match its warmth-to-weight ratio, compressibility, long lifespan, and softness. Duck Down is great for insulated clothing and equipment for all but the most serious expeditions.
	Helium Helium fabrics are exceptionally light, compressible, and soft. Their densely woven construction ensures the highest levels of down-proofing and wind resistance.
	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 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.

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