The H7R.2 Headlight from Ledlenser is a programmable headlight with two constant-on brightness output modes, a boost, a safety, and a strobe mode. Its high output mode delivers 300 lumens of light for a maximum of four hours, and its low output mode delivers 20 lumens for a maximum of 60 hours. You can continuously adjust the brightness and the strobe rate with a dial knob located on the battery compartment. If you need a very bright burst of light, use the boost function which will automatically revert to your current output mode after a few seconds.This headlight has an energy saving mode and a constant output power management mode. The energy saving mode is designed to extend battery life. It will vary the LED brightness according to the amount of remaining battery charge. The constant output mode will maintain a set LED brightness level until the battery is depleted. Both of these power management modes are executed by a built-in micro-controller and a temperature control unit. There is also a power lock function which prevents accidental battery drain.The H7R.2 is equipped with the Advanced Focus System which combines a reflector and a lens. It produces an evenly illuminated beam spot during entire focusing range. Twist the headlight bezel to focus the beam.The battery compartment is located in the back and accommodates one Li-ion rechargeable battery pack or 4 disposable AAA batteries. There are two rear LEDs which serve as a red safety light, a battery status and a charging indicator.