Grimaldi Lighting LED Bulb, 3 Pack, 3 Watts, 260 Lumens, A15 Style Bulb, Pure White (5000K), Dimmable, 25W Equivalent 3 Pack, 3 Watts, Pure White (5000K), 260 Lumens, Dimmable An A15 style bulb is smaller than a standard bulb (~1.8 inches diameter,~3.2 inches long). The bulb base is medium (E26). The dimmable range is 10% to 100%. This bulb is generally dimmable in most legacy dimmers (TRIAC) and new universal dimmers. As with all LED bulbs dimmer performance is highly variable based on the dimmer switch and fixture. You can buy with confidence that you can return easily if your specific dimmer switch produces unacceptable results. This bulb is not compatible with X10 home automation systems.