This lamp is a 120 volt, 250 watt incandescent light bulb. It is "A" (A21) shaped with a glass diameter of 2.6 inches, a screw base (E26) measuring 26 millimeters in diameter and an overall length of 4.9 inches. It has a Kelvin temperature of 4800 and is rated at 3 life hours. (GE40564)