Replaces 46' 54W T5 HO lamps. Fits into fixtures just like a T5 HO bulb. Lower power consumption. Only uses 18 watts. Fits into fixtures just like a T5 HO bulb. Pleasant shimmer effect. Even daylight look for freshwater aquariums. Reduced heat. Much less heat than T5 HO lamps We do not recommend using this LED Lamp in a fixture with metal halide bulbs. The heat from the metal halide bulbs could melt the Arcadia LED Lamp housing causing the lamp to fail.