A review by Guy Cotter, CEO of Adventure Consultants.

We do get used to certain items of equipment being designed with standard customary features so when you do see a change to the `norm’ it is easy to write it off as gimmicky or just not quite right!

I felt that way towards the North Face Inferno sleeping bag when I saw the zipper was on the top of the bag, you know, the part where all the heat can escape and hence the reason the zipper has never been on the top of any other bag I’ve seen before.

I used the -29C version of the sleeping bag on a recent expedition to Dhaulagiri this year, they also make a -40 version of the Inferno which I used on a trip to South Pole (I actually found that bag too hot even with overnight temperatures below -40C).

One of the features I look for in an expedition bag is that there is sufficient room inside to not only myself, but also my inner boots, gloves and various other items that need to be warmed up or dried overnight.

I was using another brand of bag as my basecamp bag on Dhaulagiri that was very roomy, yet I found that I was actually quite cold inside it at times, even though it had the same amount of down inside it as the Inferno.

The issue was that the down in that other bag was spread over a larger area and hence didn’t have the same insulation properties. By contrast, the Inferno -20F/-29C bag had sufficient room for me and my gear and was still warm.

For the warmth it provides, the bag is reasonably light at around 1.5-1.6 kilos and the stuff sack is very functional. I was tenting with a guy who had the Inferno -40 and he found it was so huge it took up half his pack and he was overheating on the mountain at night. It would be a fine bag for climbing at altitude in winter but for spring season when temps only dropped to minus 20C to -25C it was overkill. My philosophy has always been to get a bag that on the coldest night you will be comfortable while wearing all that other clothing you’ve been carrying instead of having that clothing being redundant.

And about that zipper on top of the bag? I realised we only spend a small amount of the night sleeping on our back anyway so it probably doesn’t matter where that zipper is!