Metal Halide Lamp, 60, 4000 K, 31200 lm (Horizontal);39400 lm (Vertical) Brightness (Lumens), 400 W, Clear, Hard Glass Material, 15000 h (Horizontal);20000 h (Vertical) Average Life, E39 Mogul Screw Base, M135/M155 ANSI Ballast Code, Non Dimmable, 4.62 in Diameter, 11.5 in Height, 61.11 % Mercury Content, 4.45 lb