I have a zero degree down bag, Wilderness Experience. Used successfully during winter trips in igloos snow caves and a few tent trips.
Last used a coupleg of years ago for a few backpacking trips. Changed to a Nemo bag because I like their “side sleeping” design. Always stored in large storage bag. Excellent condition.
Thought pics might be helpful. Two of the pics show the bag on top of an REI goretex bivy bag I’ve used for winter camping. I’ve always sold strictly local for a variety of reasons, so never posted here. But I want to make more space in my gear storage, so I’m willing to ship!