Simply does not work.
This flask looks good out of the box, but when you look inside you see that the inner part of the flask is metal rather than the glass I was expecting. I had my doubts about this so I tested the flask with a fresh pot of tea. Here's what I found.
After about ten to fifteen minutes, the outside of the flask was getting warm. This obviously meant that the internal heat was being lost. And indeed, after an hour or so, the contents were lukewarm. After two hours, they were cold.
In a side by side test, the 20 year old vacuum flask that this product was mean to replace kept the contents hot for over seven hours.
In short, this flask just does not work. Not worth considering.
Verified purchase: YesCondition: New