Nordisk Oscar -2 is one of the best fiber sleeping bags and a study in sustainability, using 100% recycled materials in the fibers.
And it's precisely the fibers and a special technology for recycling them that are among the big secrets to making such a lightweight and compact sleeping bag with such great temperature properties.
It's old soda bottles that keep you warm - that's a thought worth considering. They are simply recycled and twisted in a way that the resulting fibers are so well-insulating that they can meet the very impressive weight and warmth specifications that the sleeping bag has.
It has a heat collar so you can keep the warmth down by your body where you need it. It has a foot box with extra space for your feet and a bit of extra insulation so you can keep warm there more easily.
In addition, it has Nordisk's new curved shape that ensures you have space where you need it and where there's just wasted space, it's cut away.
The result is that there is much less volume to be heated up when you lie in it and much less volume to pack in your backpack when you're hiking.