Mountain Equipment Xenith II Down Sleeping Bag

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UOG TOP PICK – For Ultralight Summer Assurance in the Hills: Weighing just 490g with 900-fill down, targeted baffle design, and a sculpted Alpine fit, the Mountain Equipment Xenith II delivers efficient warmth and packability for cool summer nights where every gram counts.

Mountain Equipment says: 

A fully featured yet superlight bag for summer mountain use. 900 fill power down is combined with our Alpine Fit and premium fabrics.

Our Verdict

The Xenith II takes Mountain Equipment’s ultralight ethos a step further, offering reliable performance for mountain travel where pack weight matters but cutting warmth isn’t an option. At 490g (Regular), it occupies a sweet spot for extended summer trekking, fastpacking, and lightweight alpine use.

The bag is rated to 1°C for a comfortable night’s sleep, and the 197g of 900-fill down delivers that warmth with speed and consistency. Baffle mapping is thoughtfully done: vertical baffles across the chest support structure and prevent sag, while the slanted layout below the waist helps the down stay in place when shifting during the night.

The fit is close without being tight, thanks to the Alpine cut, which minimises dead air. The hood deserves special mention, low in volume, sculpted for a snug seal, and free from bulk. It wraps cleanly around the head and cinches easily, giving a secure feel without bunching or gaps. The offset foot-box offers noticeable comfort for those who sleep on their sides.

The Plasma 10D fabric feels soft and breathable, handling moisture well in settled but humid conditions. The zip is smooth and well-baffled, and the overall construction is tidy. It’s a sharp piece of kit for lightweight summer mountain use, where both thermal assurance and packability matter.

– Reviewed by Ultralight Outdoor Gear

Features

• Alpine fit maximises thermal efficiency
• Vertical box wall chest baffles & slant main body baffles
• Stitch-through baffle back
• Ground level side seams
• 5 baffle low volume anatomically shaped hood
• 3 baffle anatomically shaped and offset foot-box
• Full length Gemini zip baffle with 110cm zip and integrated neck collar
• Supplied with roll-top stuff-sack and storage cube

Specifications

• Regular weighs: 490g
• Long weighs: 522g
• Fill Weight: 197g
• Std Pack Size: 19cm x 17cm x 15cm

Temperature Ratings

*Mountain Equipment use their own ‘Good Nights Sleep Guaranteed’ rating which they believe is a more accurate number for some sleeping bags and is based not just on the EN test results but on lab testing, their own use, thermal imaging and cold chamber work, along with a lot of data analysis.

• Good Nights Sleep Guaranteed: 1°C /34°F
• Comfor: 8°C/46°F
• Comfort Limit: 3°C/37°F
• Extreme:-10°C/-14°F

Material & Construction

• PLASMA 10D fabrics throughout are incredibly light and breathable with fluorocarbon-free DWR
• 197g of 90-10 European Goose Down with a minimum fill power of 900

Help & advice:

• Mountain Equipment Extreme Light Sleeping Bag Range
• The Ultimate Guide to Lightweight Sleeping Bags
• Time-Saver Guide to Choosing a Sleeping Bag
• The EN13537 Standard
• Mountain Equipment Sleeping Bag Guide
• All About Down
• Why is ‘PFC Free’ Important?
• Recycled Content in Outdoor Gear