Frequently, a Hall sensor is combined with threshold detection, so that it acts as and is called a switch. Commonly seen in industrial applications such as the pictured pneumatic cylinder, they are also used in consumer equipment; for example, some computer printers use them to detect missing paper and open covers. They can also be used in computer keyboards, an application that requires ultra-high reliability. Another use of a Hall sensor is in the creation of MIDI organ pedal-boards, where the movement of a "key" on the pedal-board is translated as an on/off switch by Hall sensors.