I bought this liner to use with my ageing Ajungilak Kompakt Super, for use whilst climbing Kilimanjaro last week (successfully!). It's super warm, and really helps out when you just need a little bit extra from your bag. Of course, an upgraded bag will perform better, but for flexibility to have a lighter bag for normal use and then an upgrade when things get chilly this is heartily recommended. Also, as I read somewhere else before buying, this also makes a great little pillow on those days when you don't need its warmth. Genuinely a great item and well recommended.