In reply to Murderous_Crow:
Things to look for in a good thermos is:
- Metal inside and outside (There are themos with glass insides, which can't take a small fall. Plastic means it's crappy insulated)
- Screwtop, instead of stupid quick buttons. A solid screw cap is a much better insulator. You do not gave to remove the screw cap, just half a turn to be able to poor (unless you got a really badly designed one).
- A cup/screw top that goes over the screw cap; nice to have a cup and it add insulation.
- Small screw tops are better at insulating
- The larger the volume, the less surface area to volume ratio. So big is better for insulating.
- Not much difference between fancy outdoor brands and just department stores one. Price however is a huge difference...
Cheap and cheerfull:
IKEA VOLYM (slighty bendy outside, but hey cheap and effective)