Converts your 6V head lamp voltage into 12V so you can use a standard led headlight single filament. for 12 volt use. Since led uses very little power the 4 Amp ballast has enough power in a small size. Works on both 6 Volt negative ground and 6 Volt positive ground cars, trucks, tractors and motorcycles. Long warranty please set page details for further warranty information. Easy to connect for (DIY) do it yourself retrofit. The ballast is water proof and is a isolated design. Please connect the ground and input 6 volt signal to the input side of the ballast. Please connect the output of the led headlight ballast to the headlight bulb directly and disconnect or cut the headlight connections from the vehicle harness. With this led lamp ballast you can have led headlights in your vintage and classic vehicles designed and built before World War II. Works on both positive ground and negative ground vehicles. Compatible with: audio, navigation, monitoring, led, air conditioning, electric fans, solar energy, photo voltaic, solar panels, DVD, lights, motors, pumps and industrial equipment. Works good for Model T and Model A and other 6 volt cars, trucks, tractors and motorcycles. Use your 12v car radio, headlight in a 6 volt system. The red and black wire are connected to 5-11 volts input. The out wires Black and Yellow are connected to 12 volt @ 4 amps.