Dream Lighting 3 LEDs Festoon Bulb 42mm Cool White Mostly used to replace festoon halogen bulbs. Ideal for use as vehicle interior dome light. A plug-in-play replacement of the typical festoon halogen bulb. Vibration-proof design, able to withstand high levels of vibration. Equivalent to a 10W halogen festoon bulb. Innovational LED technology provides potential energy saving.