Light bars are rectangular or square LEDs which are soldered directly on to circuit boards or plugged into bases. They mostly consist of aluminium and the alloy indium gallium phosphide (InGaP). Therefore they emit light in the colour range orange-red and yellow through to green-yellow. In the typical signal colours red and green they are used amongst other applications as status indicators on machines or on computer circuit boards. A particular feature is their even distribution of light. This means they are clearly visible at long distances and from practically any angle. Light bars are often used in the industrial sector, because they are particularly robust and insensitive to shaking and environmental conditions.