MH 400w Conversion Lamp BT-37, Iwasaki Lamps. This 400-Watt Metal Halide Conversion Lamp is for customers wanting the vegetative growth benefits of an MH lamp, while operating on an HPS system. Universal design accommodates vertical and horizontal positioning. Emits 36,600 lumens. For use only in a full-size 400-watt sodium system to radiate halide light.