Metal Halide lamps, ranging from 6,500°K - 10,000°K, emit bluish purple light ideal for the veg cycle. Method Seven Metal Halide grow glasses, made in collaboration with Carl Zeiss, offer exceptional color, clarity, and protection. These durable polycarbonate lenses are silver-coated for intense light, providing 100% UV protection. Method Seven makes the ONLY lens specifically working with Metal Halide bulbs. That's crazy - because there are only a few of you growers who still love MH -  but we do it for you, because we get it.