Metal Halide lamps, which range from 6,500°K - 10,000°K, emit a bluish purple light that is ideal for the veg cycle. Method Seven Metal Halide grow glasses are manufactured to exacting standards by Carl Zeiss, providing exceptional color, clarity, and protection for the metal halide grow room. These durable polycarbonate lenses are silver coated for the intense light of your grow and your outdoor lifestyle, including 100% UV protection and great value.