Sylvania M400/PS/U Pulse Start Metal Halide Lamps are members of the high intensity discharge family which is the most efficient source of white light today. Metal Halide Pulse Start lamps provide superior performance compared to standard metal halide lamps. The specific benefits are higher Efficacy, better color uniformity, faster warm-up, improved Lumen Maintenance and longer life. More light for less energy make Pulse Start Metal Halide the most logical lighting choice for designers and corporate energy managers seeking to reduce power bills.