Well, I've been catching up on Arc news, and appearently the Arc 5 might end up being twice as bright or so as the Arc 4, which rates in at 33 lumens... which means that theoretically the Arc 5 could be 66 lumens? Wow. That's brighter than my Surefire L4 /ubbthreads/images/graemlins/smile.gif If it had identical effeciency, that would mean about 30 minutes of battery life. Pretty bright for those 30 minutes, though.