Peanut bulbs like these twin-pin guys fulfill a variety of purposes. Donot get them mixed up. Some are designed for instrument panels. Othersare designed for brighter applications, like side marker lamps. In anycase, these lamps are push-in types to be handled with care. Withinstrument panels, they install in push-and-twist sockets that fit intoa printed circuit board. For side marker lamps, they push into a socket.