Portable music players were already a coveted item around 1920, when the travel record player Mikiphone was invented in Switzerland. With new audio media such as the cassette, Minidisc, and CD, the design of the playback devices changed. The digital MP3 technology marked a major advance in miniaturization, with precision mechanics thereafter playing only a minor role. Telephones have also changed through digitalization, with landline and mobile phones taking on a similar appearance.