Mountain Equipment Xero 550 2010

The Xero range comprises Mountain Equipment’s lightest sub-zero sleeping bags. Comfort at minimum weight is the hallmark of the range. The EXL stretch baffle system ensures the bag hugs the body, so that the top quality down can keep you warm. For 2010 this bag gets even better down.

The Xero range is made to be lightweight, so the latest version uses down that has a fill power of 750, compared to the 700 fill power down of previous versions. The down is sourced after the birds are slaughtered and they specify that no down comes from live plucked or force-fed birds. This improved fill power means less down is required to provide the same level of insulation. The outer fabric is He30rs, which weighs only 29g/m2, which is exceptionally light. These materials are incorporated into a box wall design, with a ‘shark’s toe’ foot to prevent down being squashed around the foot. The foot also gets a five-baffle bull’s-eye construction to again ensure the feet are kept warm. However the big feature of many Mountain Equipment bags is the EXL system of stretch baffles, which ensures the bag hugs the body to increase warmth.

On the hill
The Mountain Equipment Xero 550 does not have any water-resistant areas on the shell so instantly I felt I needed to be a little more careful with it to ensure the down remained dry. The outer fabric is very thin and you can just about see the down inside it. But there does appear to be a good distribution of down with the hood getting a good wad along with the shoulder baffle and zip baffle. That bull’s-eye foot also feels very well packed with down. The zip gets an excellent anti-snag strip too; and indeed this was the most snag-resistant of all the bags tested. The bag feels very comfortable and the hood and shoulder collar adjustment works very well. I do like the stretch baffle system as it feels a little more cosy and keeps the bag close no matter how you sleep.

In the lab
Lab results of 15TOG / -20 deg C are very warm for a -6 deg C rated bag. We had an early sample of the Mountain Equipment Xero 550, so it is possible that in production the rating may be a little less warm this. But this temperature for the weight and price is still excellent. As the hood and foot are well packed with down and there is the EXL system this bag is definitely easily capable of being comfortable as a three-season option.

Size 220x75x50cm
Outer fabric He30rs
Inner fabric Supersoft lining
Fill weight 550g of 93/7 Hungarian goose down
Fill power 750+
Lower comfort temp rating -6 deg C
Trail temp rating -20 deg C
Packed size 19x34cm in stuffsack;19x28cm compressed
Weight bag without stuffsack 979g
Made in China
Stores across UK 100
Stockist details tel. (0161) 366 9732;

The Mountain Equipment Xero 550 has a well-designed foot, excellent zip and baffle; easy-to-adjust drawcords; stretch baffle system for to maximise warmth, However, a water-resistant shell would be better for UK mixed conditions. It’s perfect for backpacking except for not having a water-resistant shell.

Review by Graham Thompson
First published in Trail magazine Spring 2010