Great Insulation!
This is by far one of the best insulated tumblers I have ever owned.  I have hat hot coffee in it now for about 3 hours and it is still &#34;sip&#34; hot.  The outside of the container is cool to the touch.  Absolutely no heat transfer that I can tell.  My only complaint is the tops.  I would have liked to see one that is somewhat seal-able.  I have to take a star off for that but otherwise it is great.
Rating: 4 stars