Those battery runtimes are not remotely realistic. Many manufacturers, including Petzl and apparently Brunton, are blatantly dishonest about their runtimes when describing LEDs. This is because unregulated LEDs will produce a noticable output for many, many hours, but only a fraction of that will be useful light. So after 200 or 120 hours, you will be able to detect a small amount of light coming from the LED in a dark room, but that light will be essentially useless.

Other manufacturers, such as streamlight and sure-fire, are honest about their runtimes and will usually list the hours of near-full brightness and sometimes the hours of declining but still useful light, or simply the hours of useful light for unregulated lights.

If you want a ballpark figure of the realistic battery life, compare the light to a flashlight with a similar battery configuration and same type of LED(s) made by an honest company. A flashlight isn't going to pull extra power out of thin air, if 2 lights use the same batteries and LEDs, their power will be similar(although circiutry can alter the ratio of runtime to output). Or read an independant review (flashlightreview.com is pretty good). Or better yet, test the light yourself.

Just don't beleive those stated runtimes, or you may end up in the dark.