Advance High Pressure Sodium Ballast, Enclosed HID Magnetic, High Pressure Sodium Lamp, 150 W Lamp, 480 VAC, 1.7/1.0/0.9/0.8 A, 60 Hz Frequency, Pulse Start, -40 deg F Minimum Starting, Power Factor: 1, No Dimmable, 1 Lamp, Thermal Protection: Class P, Ballast Factor: 1, ANSI S56 Ballast Grade, 3.95 in L x 3.8 in W x 2.8 in H Dimensions