Metal halide lamps feature excellent luminous efficacy while simultaneously having good colour rendition; their nominal service life is high. They represent a compact light source. The light can be optically well directed. The colour rendition is not constant. Metal halide lamps are available in the light colours warm white, neutral white and daylight white and are not dimmed. Metal halide lamps require both starters and chokes for their operation. They require an ignition time of several minutes and a longer cooling-down phase before re-igniting. On some forms an immediate re-ignition is possible using special starters or the electronic control gear.