ETC 42550 Source Four 25-50-Degree EllipsoidalThe 42550 Source Four 25 50 Degree Ellipsoidal from ETC combines the energy saving power of the patented HPL lamp with a dichroic reflector and optical quality lenses. That means your gels, patterns and shutters last longer and your performance space stays cooler. No other light offers such optical brilliance. Source Four's revolutionary technology gives you a clean white beam for unequaled imaging, crisp pattern projection, and a bright, even field.