Before the shift key, typewriters had to have a separate key and typebar for upper-case letters; in essence, the typewriter had two keyboards, one above the other. With the shift key, manufacturing costs (and therefore purchase price) were greatly reduced, and typist operation was simplified; both factors contributed greatly to mass adoption of the technology. Certain models, such as the Barlet, had a double shift so that each key performed three functions. These little three-row machines were portable and could be used by journalists.