ZeroDark is a two-in-one perfect combo that comes with battery storage case and tester. This unique system holds up to 110 batteries and is also a battery organizer made of durable ABS plastic that’s sturdy, simple and easy to use. Each battery has its own designated space so it will always fit perfectly. Organize AAA, AA, C, D, 9V sizes, and small batteries; this organizer keeps every size easy to see and sort – just select what you need. The handy digital battery tester accurately displays the residual voltage, making it easy for you to get the most out of your batteries and let you know when it's time to get a new one.