Mountain Equipment Helium 250 Sleeping Bag (1°C/34°F)

Weighing less than a standard water bottle and compressing to a similarly compact size, this sleeping bag is an ideal choice for the dedicated warm-weather adventurer seeking to reduce pack weight without sacrificing comfort.

Filled with 261g of minimum 700-fill power duck down, approved by DOWN CODEX®, and protected by a robust yet lightweight outer made from 100% recycled Helium 20D fabric, the Helium 250 delivers impressive performance in a remarkably low-bulk design. It is particularly well-suited to backpackers and cycle tourers who value efficiency and minimalism in warmer climates.

A slant-baffle construction runs throughout the body to maximise thermal efficiency, enhance packability, and prevent down from shifting, which helps maintain consistent warmth and eliminates cold spots over repeated use. At the foot end, a four-baffle trapezium system ensures warmth is concentrated around the feet, while the hood features a five-baffle layout that carefully controls down placement for optimum insulation and comfort.

Inside, a 100% recycled Supersoft 20D lining fabric with a PFAS-free DWR treatment provides both breathability and long-lasting durability. The full-length Gemini™ zip baffle is designed to virtually eliminate heat loss along the zip and is reinforced to avoid snagging. Additional thoughtful features such as the low-profile magnetic Lode Lock™ closure and adjustable collar drawcords are easy to operate, even in low light.

The Helium 250 has been engineered with a refined Alpine 2.0 fit, offering a balance between technical performance and comfort. With a Good Night’s Sleep Temperature rating of 1°C (34°F), it stands out as the ideal warm-weather companion for those aiming to travel light and sleep well.

Features

Insulation

• The insulation is optimised in each baffle to deliver the best possible warmth-to-weight ratio.
• The regular size contains 261g of 90/10 duck down with a fill power exceeding 700.
• The long size includes 273g of 90/10 duck down with the same high fill power.
• All down is ethically sourced, adhering to DOWN CODEX® and RDS 3.0 standards.
• Each sleeping bag is issued with a unique DOWN CODEX® code, offering transparency on both sourcing and fill power.

Materials

• The outer fabric is made from HELIUM™ 20D, a 38gsm recycled 20-denier material that combines low weight with durability, compressibility, and reliable weather resistance. It is tightly woven to reduce wind penetration and heat loss, and treated with a PFAS-free DWR coating.
• The lining is constructed from Supersoft™ 38gsm 20D recycled downproof nylon, designed to be breathable, long-lasting, and comfortable against the skin, also finished with a PFAS-free DWR.

Patterning & Design

• The design prioritises durability and high-performance use over time.
• The Alpine 2.0 fit introduces a refined, tapered shape that improves heat retention without adding bulk.
• Slanted box-wall baffles reduce structural weight while enhancing thermal efficiency.
• The down fill is distributed strategically, with higher-density fill located in critical zones such as the underside, foot box, and hood, preventing migration and boosting warmth where it matters most.

Foot Box

• The Trapezium 4 system uses a four-baffle arrangement to retain warmth and reduce compression around the feet.

Hood

• The five-baffle construction ensures precise control of down placement while keeping weight low and warmth high.
• The hood is spacious enough for comfort yet designed to sit snugly, with dual tether drawcords to minimise heat loss.

Zip Baffles & Collars

• The Gemini™ baffle system is lightweight and low-profile, effectively limiting heat escape while maintaining zip protection.
• The Lode Lock™ system features a secure magnetic fastening with a mechanical lock, allowing for quick one-handed use.
• An integrated, adjustable down-filled neck collar adds extra insulation around the shoulders and neck.

Additional Features

• A waterproof roll-top stuff sack is included, ensuring compact packing while protecting contents from moisture.
• A storage cube is provided to preserve the loft of the down between trips, supporting better long-term performance and ideal for home storage.
  
  

Specifications

Technology

	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.
	Down 700 Down is the finest insulator that we have. Its warmth to weight ratio, compressibility, long lifespan, and softness are yet to be matched by manmade insulations. For all but the most serious expeditions, duck down is a great choice for both insulated clothing and equipment.
	Helium Helium fabrics are exceptionally light, compressible and soft. Their densely woven construction ensures the highest levels of down-proofing and wind resistance.
	Down Codex® 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. It is grounded in comprehensive and transparent auditing that ensures traceability and quality.

Detail Shots

	Using slanted box-wall baffles throughout the entire main body of the helium bags means weight is removed from the bags structure, yet they remain a significant step above a standard box baffle.
	5 baffle anatomically shaped hood.
	4 baffle anatomically shaped and offset foot-box.
	Full length Gemini zip baffle with 140cm zip and integrated neck collar with Lode Lock closure.
	100% recycled HELIUM 20D outer shell is very light and highly breathable with PFC free DWR.
	Integrated neck collar with Lode Lock closure.

More Information

Helium Sleeping Bags

Efficiently sized, supremely comfortable, and low in weight each Helium bag offers outstanding all-round performance for backpackers, cycle-tourers, and trekkers. These bags don’t skimp on features and will keep you warm and comfortable whether on a summer road-trip or an extended trek.

Shop The Helium Range

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