A person pouring drink from a thermos. Illustration photo by Pexels ... Prolonged high temperatures inside an insulated flask can also destroy the vitamins in tea, evaporate essential oils ...

The bargain bottle keeps things warm, cool or fizzy – and best of all it doesn't have that 'usual flask taste', say fans ...

Thermos is still the most recognisable name in the market, offering an extensive range of products to keep food and drink hot or cold. We tested the 1.2-litre capacity flask in bold red ...