The document summarizes an LED luminaire called the RT-ES4 that can retrofit into existing ETC Source Four fixtures. It is 90-watts, 600 times more efficient than incandescent, and matches the lumen output of a 575-watt bulb. It has variable beam angles and color temperatures between 2700K to 5000K. The luminaire reduces heat load on HVAC systems and has a long life expectancy of 50,000 hours of operation.