Easy to use, charges one battery then the other rather than both at the same time. With the USB port, you can use it with batteries as a power bank to charge other devices, it doesn't store electricity to charge batteries like I thought. For the price it's amazing, reliable and high quality. It's good enough that I couldn't justify buying a brand name that lets you charge a third battery for $50 more. Great product and I'm interested in learning more about their other products.