Most coffee makers have a glass carafe, but you can also find thermal carafes that are double-walled containers made of stainless steel. The latter have a battle between the two walls to minimize heat transfer and keep the coffee piping hot for hours. This is similar to the concept of a thermos or travel mug. While thermal models keep the freshness of the coffee intact and remain hot for a longer period of time, they are often heavy, and, unlike in the case of glass models, you cannot see how much is left in the pot. On the other hand, glass carafes can be easily broken but are cheaper than thermal models.