The Fenix LD20 LED flashlight is digitally regulated and digitally controlled. It has two output modes which produce a total of six levels of output. These modes not only allow the user to select the best compromise between brightness and runtime for any given task, but they also help to aid in an emergency. The LD20 does all this and still retains a very compact size and uses a commonly found AA battery. If you"re looking for solid reliability, digitally-regulated brightness, and compact size, this Fenix is for you.