Upgrade to better white light Easy upgrade to better white light just by changing your bulb;Improved lifetime maintenance increases time between re-lamping;Improved lumen maintenance increases time between re-lamping;Reduced spend on energy Philips MasterColor Ceramic Metal Halide Pulse Start ED28 Lamps are a better value than quartz metal halide, with longer life, higher lumen maintenance, and energy efficiency. Better quality white light in a familiar ED28 bulb shape with a mogul base;Better rated average life of up to 20,000 hours;4000K color temperature;Better lumen maintenance than quartz metal halide;Better energy efficiency Ideal for downtown areas, colleges and universities where visibility and quality of light are important.