I have it on my key chain. I've had it for about 3 weeks now and so far I'm very impressed with it. Have not tested the battery run time yet. It's rated at 150 lumens on high but I think it's more like 100. Still very bright for it's size. Medium is about 50 lms and low is about 10 lms. The only thing I don't like about it are the S.O.S and strobe modes. I find them useless. Otherwise I'm very happy with it and I think you will be as well. Worth the price IMHO. I'll test the battery time on low and get back to you later.