GU4 (MR11) Halogen Bulbs are used for spot lighting and operate with 12V. They are more energy efficient compared to incandescent bulbs. GU4 stands for the type of socket; MR11 is the shape of the Halogen Bulb. The GU4 (MR11) Halogen Bulbs are fully dimmable, with the filter on the left side of the screen you can quickly select the product you need. Buy your GU4 (MR11) Halogen Bulbs at Any-Lamp, we guarantee you low prices and fast delivery!