Worth knowingWhat the vacuum layer actually does
There are two walls of steel with the air drawn out between them. With almost no air left, there is almost nothing to carry heat from the inside wall to the outside one — which is why a vacuum flask behaves differently from a double-wall cup that simply has a gap.
What that means in practice for TI-1240: the outside stays comfortable to hold with a hot fill, and the drink is still warm hours later. We test in the region of 10–12 hours hot and longer cold, but what we can say is that it depends on the fill temperature, how full it is and how often the lid comes off. A bottle opened every twenty minutes behaves nothing like one left closed.
Ask for the measured test on this model rather than a headline number, and we will send it with the conditions it was run under so you can compare it against whatever else is on your desk.