Our Yield Lab 400w Metal Halide bulbs are designed specifically for the vegetative stage of plant growth because of the blue wavelengths they emit, promoting the healthy development of stems and leaves. 400w MH bulbs are perfect for leafy greens and the vegging stage in your flowering plant\'s life cycle. Providing 110,000 lumens of light to your grow, these bulbs will give you 10,000 hours of light- well beyond the lifespan of inferior bulbs on the market! * Total Wattage: 400* Color Temperature: 5500K* Pass UL and CE tests* Fits with all 400w HID grow light reflectors with E39 mogul base sockets* Compatible with magnetic and digital ballasts