It is a basic metal halide lamp with a 10,000K spectrum. HID stands for High Intensity Discharge. HID refers to a family of lamps that utilize a discharge/arc for emitting light which includes metal halide lamps. What makes it different is the bulb size format (tubular G12 Bi-Pin base lamp). G12 base metal halide lamps have been available for many years but never really been offered to the North American aquarium market. The compact bulb size does allow for efficient and different reflector designs. These are great for spot lighting. They are commonly used for commercial lighting but in a lower color temperature. Higher color temperature G12 base lamps are also utilized in entertainment/event lighting fixtures (moving heads, spots and scanners).