Our CoolLED pE-4000 is installed on the spinning disk confocal. Our use of the pE-4000, for now, has been mostly limited to specimen finding and focusing. We can certainly already say that it is a very powerful and very flexible system compared to the traditional fluorescent lamp that we've installed on the other microscopes. The fact of not having neutral density filters makes the variation in light intensity much more linear. To date, we have verified that for many samples it is sufficient to use LEDs with a maximum power of 5-10%. We are also very confident about the maximum lifespan of LEDs compared to that of classic fluorescent lamps. The system interface is very user friendly, both through the Nikon NIS software to its controller.