Often used as status indicators, in displays, or to check circuit function in prototyping and testing, these bulbs have wire terminals to directly install onto circuit boards. As LEDs, they last longer, are more efficient, and produce less heat than other types of bulbs. Vibration won’t cause these bulbs to malfunction. Brightness is measured in lumens; the higher the lumens, the brighter the bulb. They require a resistor (sold separately) to limit current.