I have a Surefire Nitrolon, and I got the rechargable set up for it. I use it at work a lot. It will run about 20 to 30 minutes on a charge with the 65 lumin lamp. I love it. As for endurance, I can't count the number of times it has been dropped on the concrete floor. Falling out of a pocket, or getting knocked off a work bench or something. Used it from 100* down to -10*, and have never had a problem. I have had it about two and a half years, and it is still on the first bulb. Same battery, also. I charge it about 3 to 4 times a week, sometimes more, and haven't noticed a drop in run time yet. Only thing I don't like, is they don't make a LED head for it.