Osram HO Metal Halide (MH) Lamp, 400W (Horizontal)This lamp provides a higher light output than comparable standard metal halide lamps. These lamps are designed for use where an increased light output and a longer life is required. This lamp is optimized for horizontal operation. The uniquely designed arc tube results in a peak performance and a substantial increase in initial and mean lumens. Improved arc tube design Increased light output Up to 20,000 hours average rated life Energy efficientup to