Mountain Equipment Xenith I (5°C)

A superlight, hoodless sleeping bag crafted for situations where every gram matters.

The Xenith I is designed to deliver maximum warmth at minimum weight. This ultralight, hoodless sleeping bag is made for those who count every gram. It combines premium 900 fill-power goose down with the remarkable PLASMA 10D fabric, providing reliable comfort, night after night.

The Extreme Light range stands among the finest lightweight sleeping bags available today, offering an unmatched balance of exceptional warmth with minimal weight and compact pack size. Most importantly, this performance is achieved without compromising on fit or the features essential for extended use in mountain environments.

Previous generations of the Xenith sleeping bags earned a loyal following among the brand’s team of climbers, having accompanied them on some of the most demanding and committing alpine ascents in the Himalaya, Karakoram, and Alaska. At the same time, they have proved themselves on classic climbs in Patagonia, Yosemite, and the European Alps, as well as on long-distance treks and ski tours where every gram truly counts.

Now fully re-engineered, the Extreme Light series — which includes the Xenith I, II, and III — has been refined across the board. The updated designs draw upon thousands of nights of experience in the field, shaped by the brand’s deep expertise. Since 1961, specialist down sleeping bags have been at the heart of their craft, and they continue to be a passion for the design and development team.

The entire range makes use of ultralight, breathable, and highly compressible PLASMA 10 Denier fabric, paired with 900 fill-power goose down. This combination ensures an impressively low weight and small packed volume, all while maintaining comfort. But premium down alone is not enough — precise control of insulation is vital. Vertical box wall baffles across the chest and slanted baffles throughout the body hold the down exactly where it is needed for optimal warmth. This level of design sophistication is typically reserved for heavier expedition-grade bags.

Many ultralight sleeping bags reduce weight by compromising on dimensions and key features — trimming length and width, using half zips, and simplifying hoods and footboxes. While this approach may deliver low numbers on paper, it often leads to reduced comfort and insulation in real-world conditions. This brand takes a different path, ensuring that their bags are as functional in the mountains as they are on a specification sheet. The Extreme Light range includes full-length, high-quality zips, advanced footbox designs, and — in the Xenith II and III — shaped hoods and integrated neck baffles. These are sleeping bags designed to be a pleasure to crawl into, whether at a scenic mountain camp or on a narrow bivvy ledge high above the clouds.

Features

• The PLASMA 10D fabrics used throughout the design are exceptionally lightweight and breathable, featuring an FC-free DWR for enhanced performance.
• It is insulated with 148g of 90-10 European Goose Down, boasting a minimum fill power of 900 for superior warmth.
• The alpine fit is engineered to optimise thermal efficiency, ensuring maximum heat retention.
• Vertical chest baffles and slanted main body baffles contribute to even down distribution and improved insulation.
• A stitch-through baffle back enhances durability while maintaining a lightweight structure.
• Ground-level side seams are designed to reduce heat loss and improve overall warmth.
• The anatomically shaped and offset foot-box provides a natural and comfortable fit for enhanced sleeping comfort.
• A full-length Gemini zip baffle, featuring a 110cm zip and an integrated neck collar, helps to seal in warmth effectively.
• It is supplied with a roll-top stuff sack and a storage cube for convenient packing and organisation.

Specifications