The SureFire KL4 LED Conversion Head provides digitally regulated LED technology for their E2, E2E, E2O, and E2D flashlights. The primary benefit of LEDs over incandescent lamps is runtime. Because LEDs produce light more efficiently at lower wattage levels, batteries that would be useless in an incandescent flashlight often have enough power to run a LED module for an extended period of time.
Normally, LEDs do not produce a steady amount of light throughout the run-time of the battery. To ensure a consistent light output for as long as possible, SureFire has created and installed a digital regulator circuit into the KL4.
The KL4 features a high-output 5W LED that delivers a 100 lumen beam for one hour.