I bought this flask to keep tea hot overnight but it did not meet my expectations. The first time I used it, after 7 hours the tea was lukewarm and had turned almost black in colour. I think that the metal interior was to blame for the change in colour but why it didn't' keep the liquid hot I don't know. I have tried it twice since with no success. The two stars are because it looks to be well made and the case also looks good quality but I feel that having the metal interior, while this makes it unbreakable, has been a mistake.