The WEST MARINE Festoon 39mm LED Bulbhas been designed as a replacement and upgrade for standard halogen, Xenon and incandescent filament bulbs, offering dramatically lower power consumption and heat generation, while having much greater lifetime and shock resistance. For even greater light output and quality as well as higher efficiency (more light per watt) please look to our Premium series bulbs. This bulb replaces and has similar brightness to 3 to 5 watt Red Halogen/Filament Festoon bulbs. Fits many 36-41mm sockets. This is the standard length festoon. 11-14VDC input range. White bulb cross reference #'s 3910, 3423, 3425, 6411, 6423 6461, 3710, 6418, 6486X, 6461, 6418LL. 60 max lumens, radiates to one side of the fixture. Note this bulb is polarity (+/-) sensitive, if it fails to light when inserted into the fixture, remove the bulb, flip 180 degrees and re-insert. Dimmable.