I don't think I believed that this would work as well as it promised that it did--but it did. I put iced tea--with ice--in my bottle at 7am, and at 1pm, there is still ice in the bottle. And at 5pm, it's still very very cold. It's amazing, and I use it all the time. Haven't tried it with hot beverages, but if it's anything like the cold, it'll work just beautifully.