VIVOSUN 1000 Watt Metal Halide MH Grow Light Bulb Lamp - Enhanced Blue and Violet Spectrums CCT 4200K, 105,000 Lumens 1000W VIVOSUN MH bulb compatible with electronic and magnetic ballasts, 105000 Lumens, E39 Base Optimized blue & violet spectrum and high PAR (Photosynthetic Active Radiation) to stimulate flower growth and enhance fruiting Extra-low lumen depreciation: maintaining over 90% of initial lumen output after running for 5,000 hours Startup Time: allow 2-3 mins for full bright. After power off, do please wait at least 5 mins before striking again Lifetime: 24,000 hours VIVOSUN dimmable electronic digital ballast is the best choice for metal halide grow light lamps. The dimmable setting of ballast should be the same watts as the bulb when starting, or your bulb may not be lighted up. The extra setting is to adjust the brightness (lumen) of the bulb. Different lumens have different effect on the plants. The ballast can&#039;t ignite lamps when it is hot. When reigniting the lamp after shuttingdown, please wait several minutes to give time for the lamp to cool down.