The high pressure sodium lamp series of HID lamps incorporates solid sodium, mercury and xenon or a neon/argon gas mixture within the arc tube. This combination of metals and gasses produces an orange-white light in the high-pressure version and a yellow light in the low-pressure model. Both lamps boast a luminous efficiency that is much greater than its mercury vapor or metal halide counterparts. Typical applications for high pressure sodium light bulbs are Street lighting, industrial hi-bay, parking lots, building flood lighting and general area lighting.