The sleeping bag liner / cloth sleeping bag is instead of sleeping bags. In the mountain huts, they provide blankets and pillows, but they ask that people take cloth sleeping bags so they don't have to keep cleaning the blankets everyday... The idea is that it makes it lightweight for people walking up in to the mountains, ie they don't have to take a full sleeping bag.  Cloth sleeping bags can be purchased from places like Millets, Field and Trek, Go Outdoors, etc. They are usually either silk (expensive) or cotton (cheap) - take a look at http://www.millets.co.uk/camping/sleeping-equipment/sleeping-accessories/product/095007.html for a deal that Millets are doing online at the moment.   Read More ...