As a photographer, I use tons of batteries for my flashes and triggers at weddings and on shoots and when the flashes start to not cycle as fast or misfire, I need to throw out my batteries and put in new ones. Well I typically don't throw them away, I just store them to use in lower powered things like computer mouse, etc. But I finally got something that helps me know weather the batteries are dead or still good. This product will save me money in the long run. I love it, works greatSee full review