Ceramic Metal Halide (or CMH) grow lights are perfect for illuminating small spaces with the highest quality light available indoors. These compact bulbs give off an optimal light spectrum for all phases of plant growth. When quality is a concern, use CMH lighting as a supplement or main light source to encourage vigorous growth and extreme oil production. These bulbs are available in 315W, with either a mogul base (E36) or a pin base (PGZX18), and in 3,000K or 4,200K color temperatures and require a specialized 315W CMH ballast to operate. Free Shipping available!