I looked up the NSN 7520-00-559-9618 and it listed Case, Maintenance, Operational OD Cotton.
I don't know for sure that is correct but with that number this is the result I found. The image included didn't look exactly the same but it also looked more modern. Hope this helps.
Information
Warning: This is a relatively older thread
This discussion is older than 360 days. Some information contained in it may no longer be current.