Unissued are the ones that were never in service. Those were never issued to military. Does not have refurbs marks on it. I guess you call it NOS which I still don't agree on because Russian and Chinese are different by stamped triangle. Chinese are not marked at all.
It is noticeable even to someone who has never seen unissued one in their life the condition of unissued one when you hold it. Just ask people who bought from us before.