SUPREME - Double Ended 1000 Watt Metal Halide MH 1000W Grow Light Bulb Lamp - 3 Pack * Features High Blue Spectral Ratios for Great Photosynthesis Efficiency and Vegetative Growth * Feature low iron (Low-E) glass for enhanced UVA and UVB penetration to your plants for higher quality and yield! * The 6.5K Metal Halide is the best spectrum used for vegetative growth to encourage shorter node spacing and bushier plants. * Full Spectrum 1000W light optimal for vegetative growth. * Is to be used during vegetative growth, and during the last 7 to 21 days of bloom to allow better ripening and finishing.