GE Appliances HID Ballast, Magnetic, HID Metal Halide Lamp, 400 W Lamp, 120/208/240/277 VAC, 1.06 to 2.45 A, 60 Hz Frequency, Pulse Start, -20 deg F Minimum Starting, Power Factor: 0.9, 1 Lamp, Ballast Factor: 1, Core and Coil Enclosure, 5-1/4 in L x 1-1/4 in W Dimensions