Diode Dynamics 29mm HP6 LED Bulb - Blue (Pair)Features Direct replacement for factory 29mm festoon bulb Increased output with LED appearance Plug and play simple installation Overview Design. The 29mm HP6 LED bulb is a direct replacement for any 29mm size bulb commonly found in door lights dome lights and trunk lights in many vehicles. Populated with eight high power LEDs arranged in an omnidirectional pattern the HP6 upgrades the factory yellowish incandescent bulb to a more modern LED