During fabrication, LEDs grow in the form of a crystal wafer. A 2-inch diameter wafer can carry more than 20,000 LED chips. Colour and intensity variations are common across a wafer. LED suppliers can supply LEDs “binned” into various groups by wavelength, luminous flux, voltage drops, and other characteristics. E.g. Select LED’s from a particular colour bin to minimise visual colour differences between an array of different LED’s.