Keystone Technologies Electronic Fluorescent Ballast, Type HL, 120 to 277 V AC, 50/60 Hz Frequency, Instant Start, 0 deg F Minimum Starting, Total Harmonic Distortion: 10 %, Power Factor: 0.97 to 0.98, Thermal Protection: Class P, Ballast Factor: 0.88 to 0.96, NEMA 1 Enclosure