I have ordered a total of 50 pieces of this spot and changed my GU5.3 GU10 installation. The spots are wonderfully bright and are dimmable. Even on conventional dimmers. They replace problem-a 50 Watt spot. Unfortunately humming / whirring the spots if they are dimmed audible. That is why a star deduction. Some also humming softly in ungedimmtem state. Strangely, some hum on the same dimmer and other not very strong again. Have a total of 4 different types of dimmers and everywhere the hum problem exists.