Glass lined thermos
A while back I mentioned I had found a personal size glass lined thermos to carry a cup of tea with me. Sadly it had been discountinued. When I was looking for something else I came across [this](https://www.amazon.com/gp/product/B075P5M38G/ref=ox_sc_saved_title_7?smid=A2L77EE7U53NWQ&th=1) glass lined travel mug. It is the exact same one I have carried for years.
It doesn't keep your tea hot for hours. It does keep it warm for a good amount of time. When I am traveling I will put some oolong in there and drink it grandpa style.
I keep a couple replacements on the shelf, because you will drop it at some point and it will break. Though I have dropped my current one multiple times and it's still going strong. The cap seems to be where the heat comes out, so maybe a cover would help to keep it hot longer.
Enjoy my tea loving friends.