Taking my 3-season to 4 season - Big Agnes McKinnis Liner 650 DownTek with Right Zipper

I am very happy with this bag. I am generally a 3 season camper/backpacker, but I do go on 2 winter trips each year. I added this to my Big Agnes LuLu to give me the extra warmth to sleep comfortably on those trips. It compresses well, so It only increases the size of my bag in its compression sack slightly. For super cold nights, I also have a Big Agnes wool sleeping bag liner. It also allows me an ultra-light sleeping bag option on mid-summer nights when camping at base of the mountain before a climb. I think it is great to have layer options for my sleep system like I do with my clothes.