+1 for the Zojiroshi. I've owned a variety of vacuum flasks and it's by far the best. Years later and my tea is still scalding hot ten hours later (I usually let it cool a bit after steeping before I put it in because it protects too well). It's gone on dozens of flights and journeys with me and other than a few scratches looks and feels as good as the day I got it. It's also trivial to disassemble and clean.