Mercury vapor lamps, Metal Halide and High Pressure Sodium bulbs are part of the HID family of bulbs. Light emitted from metal halide is white and from High Pressure Sodium bulb is amber orange. While mercury lamps produce white light with a bluish-green tint due to mercury's combination of spectral lines. Mercury vapor lamps is the least efficent member of the HID family due to lower light output.
Mercury vapor lamp, metal halide lamp or high pressure sodium??