Mark 7(R) 0-10V, Electronic, Fluorescent Dimming Ballast, Ballast Start Type Rapid, Input Voltage 120 to 277V AC, Number of Bulbs Supported 2, Max. Bulb Watts 17 W, 25 W, 28 W, 32 W, Ballast Bulb Type T8, T8U, Dimming Yes, Dimming Type Full Continuous Dimming, Dimming Method 0-10V, Dimming Range 100 Percent to 3 Percent, Min. Starting Temp. 50 Degrees F