The early red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators
were so small that plastic lenses were built over each digit to make them legible. Later, other colors became widely available and appeared in
appliances and equipment.
Early LEDs were packaged in metal cases similar to those of transistors, with a glass window or lens to let the light out. Modern indicator LEDs are
packed in transparent molded plastic cases, tubular or rectangular in shape, and often tinted to match the device color. Infrared devices may be dyed,
to block visible light. More complex packages have been adapted for efficient heat dissipation in?high-power LEDs. Surface-mounted LEDs further
reduce the package size. LEDs intended for use with?fiber optics?cables may be provided with an optical connector.