Fluorescent Lamp, T6, 15 Watt, 18", Day Light 6500K, 85 CRI. Operate in standard 18" (F15T8) fixtures, with T8 electronic or T5, , electronic ballast, Medium BiPin (G13 base), Lumen output 1200. This lamp had twice the output of a standard F15T8. Warranty - 6 months. Electronic program start or rapid start ballast for best performance.