The thermos plays his role very well it keeps the water hot for a long time ... Personally I share in general around 14h so I boil water just before, for the bottle of 240ml 4H-4:30, I need 2min timer to make it a good temperature (thermometer support). for one evening around 8:30 I must always 4min max for a 240ml. J 'was selected in the range Advent bottle so I will encounter no problem of size but honestly I think no matter bottle brand that one chooses from this product seems universal. the whole is very well thought out and it is compact.