This led transformer driver is used to power low voltage 12v led bulbs and strip lighting led bulbs require a constant current to work properly sometimes a normal 12v transformer will work correctly with led bulbs but in some cases the lifespan of the bulb will be reduced this led driver is the perfect product to replace the 12v transformer which is currently powering your existing low voltage bulbs this led driver will power led bulbs up to150 watts for example if you buy37 x4 watt