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 Halogen/Filament Festoon bulbs on 24 volts. Fits many 36-41mm sockets. This is the standard length festoon. 22-28VDC input range. Cross reference #'s 3910, 3423, 3425, 6411, 6423 6461, 3710, 6418, 6486X, 6461, 6418LL. Dimmable down to 12V at very low brightness and power. 65 max lumens, radiates to one side of the fixture. Commonly used in 24V automotive, marine and RV dome and interior lights, companionway lights. 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.