-discharge protection switches the lamp off and prevents the voltage in the cells falling below 0.9 volts. Although the discharge protection reduces the actual burn time by preventing the full use of the cells capacity, it does however greatly increase the life expectancy of the cells. This protection additionally limits the build up of pressure within the cells and thus reduces the risks resulting from the production of hydrogen gas. The discharge protection does not switch the lamp off suddenly, instead:
-a low capacity warning informs the user with 3 blinks of the halogen Bulb, of the imminent end of the burn time. This warning can be heeded in the professional versions and the lamp can be switched over to a reduced power setting, thus extending the time before the lamp turns itself off.

professional version:
This version has all the features previously mentioned plus:

-a variable power setting giving 25%, 50%, 75%, 100% of the maximum power output of the halogen Bulb