Advance, RELB2S40N35I, Rapid Start Electronic Fluorescent Ballast, T12 Lamp, 40 W Lamp, 30 to 72 W Wattage, 120 VAC, 0.25 to 0.61 A, 60 Hz Frequency, Rapid Start, 50 deg F Minimum Starting, Total Harmonic Distortion: 20 %, Power Factor: >0.98, No Dimmable, 2 Lamps, Ballast Factor: 0.85, NEMA 29 Enclosure, 70 deg C, Metal, 9.5 in L x 1.3 in W x 1 in H Dimensions,