Fenix is one of the best products I have ever purchased. So impressed with it, I bought one for my daughter. We do everything from track deer to shine frogs with ours. Mine is the PD30 and my daughter has the E15. Both run off the cr123 batteries, mine takes 2 and hers one. Hers has a max lumens of 140 and I had read that if you keep the lumens under 160 it will prevent the light from getting so hot to the touch that it will burn you, so that is why I got her the lower lumens one. She wears hers around a neck lanyard as it is so small. Most of the time, I use mine on the lower lumens setting anyways. Battery life on these fenix lights are great and VERY durable and well built.