A retro kettle is round and has a design similar to an old-fashioned kettle. In addition to the design, the color makes a kettle retro. They come in pastel colors, but the retro kettles in black are also popular. Do you want to keep a close eye on the temperature of the water? Choose a model with an analog temperature meter. That's useful if you don't want to bring the water to a full boil, for example.