Metal halide lamps use chemical compounds of metal halides and metallic vapors to illuminate the lamp. They are the most popular HID lamps on the market with many indoor and outdoor applications. They have high efficacy, good color rendition, long life, and a wide range of colors and wattages. They are the number one HID lamp to use if people are present in or using the space. Common applications include gymnasiums, indoor arenas, malls, car lots, and hotels.