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How does the FLSK thermos bottle perform in tests?

Wie schneidet die FLSK Isolierflasche im Test ab?

Before you buy something, you want to be sure that everything fits. This also applies to the FLSK thermos. How good that there now are several independent tests on the Internet that you can use for orientation. So that you don't have to laboriously search through the individual tests, you will find an overview of the most important test results here. True to the motto: Trust is all well and good, but control is better. :-)

Insulation & density

Can the FLSK really keep beverages hot for 18 hours and cold for 24 hours? This was the question that was the focus of most tests of thermos flasks. In all test series, FLSK kept its promise and surprised the testers with its endurance. The FLSK’s good sealing capabilities were also proven: After 24 hours, the mineral water filled into the bottle was still absolutely sparkling in the test. confirms this and also advises to tighten the cap well for carbonated beverages. This is also sensible from our point of view because locked up carbonic acid can build up a lot of pressure...


Many testers praised the uncomplicated cleaning of the FLSK drinking bottle by hand with hot water. This is made possible by the type 304 stainless steel, which is food-safe and does not take on any taste. says: "No matter whether it is warm tea or cold juice - rinse it out vigorously once and you no longer know what was in it before". Quite rightly, there is a warning against cleaning in the dishwasher, as this can damage the paint.


The minimalist design of the FLSK vacuum flask is particularly striking in the test. This makes it a real lifestyle object. Compared to other bottles, the FLSK also convinces with its many variants. Whether you like plain black or bright red - you are sure to find your favorite color here. 350 ml or 1000 ml capacity? You decide. A small drop of bitterness: The lid of the FLSK cannot be used as a cup. Therefore: Either take an extra cup with you or drink directly from the FLSK. According to, the bottle opening is exactly the right size to drink from it comfortably.

Environment & health

In terms of sustainability, the FLSK is one step ahead: isn’t the only one that is pleased that the FLSK is completely free of pollutants and BPA. Thanks to its resistance to falls and impacts, the vacuum flask is said to have a long life and a good environmental balance.

Test conclusion for the FLSK drinking bottle

The FLSK is at the top of all tests. With its high-quality workmanship, it clearly stands out from cheap products. even calls it "the best thermos flask in luxury quality". Testers are particularly impressed by the fact that the FLSK vacuum flask really does keep liquids warm for 18 hours. Don't believe it? Try it out!

The FLSK vacuum flask in the test - FAQ

Has the FLSK been evaluated by Stiftung Warentest?

No, Stiftung Warentest has not yet tested the FLSK vacuum flask. If they do, you will of course find out here.

Were the tests really independent?
Yes, we at FLSK do not pay a tester to give us a good rating. Why? We don't need to. We are absolutely convinced of our product and believe that it speaks for itself.

Can I test the FLSK vacuum flask myself?
Of course! Choose a color in the shop and have fun with your new FLSK water bottle. If you are not satisfied or have problems with your bottle, simply contact us. We will find a solution.

Where can I find the mentioned tests?
Would you like to read more about the individual tests?

Then have a look here:

Finde Deine Lieblings-FLSK.