Ya when i got my bike the guys who had it before me screwed it up way bad, and my lights were so dim no matter what i did and i couldn't figure it out. i believe thats the voltage regulator, but i dunno how its supposed to hook onto the lights. so i just tore off the lights they jerry-rigged onto the bike. but my guess is somehow thats supposed to make the headlights bright, i just don't know how it is supposed to be wired up