High quality bag
My wife bought me this bag for Fathers Day. I'm just back from a week backpacking, most of which was spent between 11 and 12K elevation. I don't know the low temps however there were hard frosts most mornings so it was below freezing, probably by several degrees. This back is designed for someone who turns inside the bag, not with the bag like in a true mummy. 60% of the down is on top so if you turn with the bag your back will get cold if it is a cold night. I never got cold. I was just wearing undies and a light polar tech top. I used to wear mid weight long johns in my old bag. I'm a cold sleeper. I went to the Sea to Summit web page to learn about their products. They use the EN temperature rating system and their comfort temp is 23F with 12F as the lower limit. If you are a cold sleeper you will probably get cold at 12F unless you had on some clothes in the bag. It is duck down. I did some research before buying and in general goose down is better, however good quality duck down is just fine and the best down is eider down which is duck down (this bag is not eider down though). Sea to Summit sends a down quality certification with the bag as well as a compression stuff sack (nice), a storage bag and a wash bag with instructions on it on how to wash the down bag. The zipper never snags and the bag lofts nicely when you unstuff it. I'm 5'11'' and had to get the long length. My shoulders were almost out of the bag on the reg length. The hood works well if you are just a back sleeper. I use the hood to enhance my pillow since I am a side and stomach sleeper. This is the best sleeping bag solution I've found for an active sleeper who does not like the confinement of a true mummy bag.