Extreme Light Sleeping Bags

Extreme Light

Fireflash | Firelite | Firefly

The lightest, most efficient bags we have ever developed. If you want reliable warmth for minimum weight, look no further. Their advanced design and cutting edge fabric technology has opened up a new standard in superlight bag construction. Developed for alpinists, ultra-distance backpackers and mountain athletes these bags will help you reach your destination faster, more efficiently and more comfortably than ever before.


Built better

Our Extreme Light series of sleeping bags have become the bag of choice for those looking for an exceptionally light bag with a reputation for outstanding performance and reliable warmth.


Now boasting unparalleled loft thanks to the use of 900 fill-power Goose Down and constructed using an entirely new Alpine 2.0 Fit block, each of the 'Fire' bags have an ultra-premium feel that can excel in almost any environment and for almost any user.


Features | Fill

Down is a unique and exceptional insulation. It is more compressible, longer-lasting, and offers better warmth for its weight than any other fibrous insulation, achieving this through a structure that traps maximum still air while weighing as little as possible. Geese, Ducks and Swans all possess down feathers underneath their flight feathers, but as all of Mountain Equipment’s down is a by-product of the meat industry, our down is only sourced from Geese and Ducks. The down is removed from the birds at slaughter and processed to make it clean, hygienic and fluffy.


900 Fill Power Goose Down

Our finest goose down and amongst the world’s very finest down. With a minimum down cluster content of 90% and individually tested at the point of filling to ensure a minimum fill power of 900. DOWN CODEX® approved.



In 2009 Mountain Equipment became one of the first outdoor brands to introduce independent auditing of our down supply chain. Quietly introduced, without fanfare or press-releases, DOWN CODEX® set out to understand an industry and supply-chain that was largely ignored and certainly little understood.


All products contain a code that can be entered into our DOWN CODEX® website to trace the down that they contain. Not only can you identify the source of your down but the audit relating to that source and the down batch test results can also be viewed.



Features | Fit

The fit of a sleeping bag is crucial in optimising performance. A well-fitting sleeping bag is not only highly comfortable it also reduces dead air space and maximises thermal efficiency.

Alpine 2.0 Fit

Slightly more tapered in the upper body and in the legs than our Mountain Fit, our Alpine Fit maximises thermal performance while minimising weight.


Our time-tested EXL® system, a patented technology developed to provide extra warmth and extra loft. It adds no weight but minimises dead airspace around the body, reduces drafts, and pulls fabric away from the down allowing it to loft maximally.


Features | Fabric

Fabric technology is advancing all the time and we continually seek out those fabrics that offer the lowest weight, maximum breathability, compressibility and comfort.

Plasma™ 10D

One of the lightest downproof fabrics on the planet. Perfect for alpinists and backpackers for whom weight is absolutely critical. Despite being just 26g/m2, the fabric has exceptional tear resistance, giving you peace of mind on longer or more remote trips. It also has incredible air permeability, allowing for extremely fast drying and exceptional comfort.

Features | Baffles

Baffle structure is crucial to the performance of down sleeping bags. Without it, even the best quality down will not loft and insulate to its full potential. Baffles affect a sleeping bag’s durability, weight, and the migration of down inside them – they are the building blocks from which sleeping bags are made.


Our neck baffles and entry-zip baffles are vital in reducing the ‘chimney effect’ of hot air flowing out of the sleeping bag’s openings, and are also useful in reducing the ‘bellows effect’ of the movement of a restless sleeper pumping warm air from the bag.

Slanted Box Wall Baffles

A slanted box wall baffle takes the classic box wall and offsets it to reduce thermal bridges and increase thermal efficiency. It also offers improved down migration control. An excellent lightweight construction technique.

Neck Baffle

Specifically designed for Extreme Light models, a significantly lighter yet highly thermally efficient replacement for the conventional neck collar. Used in conjunction with our Gemini zip baffle.

Lode Lock™ Collar Closure

Our Lode Lock™ collar closure with its low profile auto-locating closure combines all the advantages of a magnetic fastener with those of a mechanical lock. Rendering the traditional press-stud collar closure practically obsolete, its one handed quick release closure uses two captivated internal magnets to draw the locking mechanism together and ensure that once connected it cannot be accidentally opened. The result is an insulated collar that is more efficient and easier to operate. The collar’s down density is optimised so it moves with the user and contours to the body, while captive and elasticated drawcords ensure easy adjustment.

Gemini™ Zip Baffle

Our Gemini™ baffle is found throughout almost our entire line of sleeping bags. It is a unique zip baffle system which replaces the bulky, down hungry twin draft tubes used traditionally on cold weather bags. The Gemini™ system is light, efficient, low bulk and supremely protective. It is grown on to the sidewalls of the sleeping bag: the integrated zip baffle utilises a continuous V-baffle system paired with a shaped and stiffened underside. With a greater contact area than a traditional tubular set-up, heat loss by convection is significantly reduced and radiative heat loss minimised. Tested through every step of its development, it eliminates heat loss almost entirely and at a fraction of the weight and bulk of more traditional methods.

Good Night's Sleep Guarantee

Every Mountain Equipment sleeping bag comes with a separate ‘A Good Night’s Sleep Guaranteed’ temperature rating.










Features | Hood and Foot Piece

The head loses a lot of heat and is very sensitive to changes in temperature, making good hood design crucial to the performance of any sleeping bag. A good hood will also keep the neck warm and reduce the ‘chimney effect’ of hot air escaping the body of the sleeping bag.


Cold feet can spell the end of a comfortable night’s sleep or even the end of an expedition and we have unrivalled experience in designing innovative sleeping bag foot pieces. By controlling the down in a sleeping bag, the foot is kept warmer, and ensuring the foot piece fits perfectly around the lower body is crucial.

DC7 LV Hood

7 baffles provide exceptional down control for long-lasting performing and excellent insulation. Smaller than our previous headline hoods, the DC7 LV reduces weight, has less deformation when cinched down small, and offers single handed closure and easy-run dual tether draw cords for greater ease of use in extreme conditions.

Trapezium 4

A four baffle foot piece featuring our unique Bulls Eye™ Technology and offset Sharks Toe™ foot that is engineered for our lightest technical sleeping bags. Its baffle construction restricts down migration whilst keeping weight and bulk to a minimum.


Discover the Range

Fireflash | Firelite | Firefly

GORE® THERMIUM™ 10D outer shell is durably light, highly breathable and rain-resistant

The warmest of our lightest bags. With 900 fill power down and optimised fit this is the perfect choice for going fast and light in the mountains.


Weight: 950g / 2lb 1.5oz

Good Night's Sleep Guaranteed: -16°C/3°F

Expedition fit with EXL® system is both roomier and has improved loft and thermal efficiency

For ultra-light backpacking and alpinism it is difficult to conceive a bag so reliably warm being any lighter. Perfect for high mountain use during the summer and at lower altitudes in Spring and Autumn.


Weight: 770g / 1lb 11.2oz

Good Night's Sleep Guaranteed: -9°C/16°F

Engineered to withstand extreme cold in the most hostile environments on eaGORE-TEX INFINIUM™ 10D outer shell is durably light, highly breathable and rain-resistant

As efficient a bag as it is possible to make with exceptionally high quality down and optimised fit, this ultralight bag will pack a punch in any high mountain environment during the late spring and summer.


Weight: 550g / 1lb 3.4oz

Good Night's Sleep Guaranteed: -3°C/27°F


Explore our Sleeping Bag Range

Get some sleep, tomorrow is a big day.

Perfectly adapted, the Mountain Equipment range of synthetic and down filled sleeping bags are the choice of today’s leading alpinists and arctic explorers. Ensuring comfort, protection and reliable warmth in the most extreme of environments. 100% of our down is Down Codex® approved and comes from independently audited and traceable sources.


Discover the range

Extreme Alpine

Extreme Expedition