A thermos is a very useful thing, without which it will be difficult to be on the road or on a long hike. After all, thanks to a thermos, you will always have hot tea, coffee or food with you. Of course, in our time to buy a thermos is not at all difficult. Their choice is so large that it is sometimes difficult to determine something suitable for yourself. Before making such a purchase, you need to remember one main condition: how long this thermos is able to keep warm. The reliability of the cork is also important, its ability to hold liquid without spilling.