Retrofit light bulbs are designed to replace inefficient or burnt-out CFL and HID lamps. Retrofit lamps provide the easiest and most cost effective incorporation of LED technology that you can install in existing fixtures. They are constructed with hundreds of stand-alone light emitting diodes (commonly referred to as LEDs) that are evenly spaced around the entire shape of the lamp.
LED retrofit lamps are up-to 80% more efficient than traditional metal halide, high pressure sodium and compact fluorescent lamps. Due to their low up-front costs, they are more and more popular for customers looking to install LED technology, rather than replacing the entire light fixture.