UPDATE - In fairness to the manufacturer, I thought I should update my original review. I still hold that it should be clearer that this is not a stand alone charger and that you need power to operate it. I got past that and decided to keep it for a few reasons. First, I bought a 65W USB C adapter and the rate of charge is SIGNIFICANTLY faster than what I was seeing with my old 12 W adapter. Very happy with that. All in, I decided that with the fast charge rate , state of charge data, dual battery charge capability, and build quality, it will work for me. Upgraded the rating accordingly.ORIGINAL REVIEW - I bought this thinking it has it's own on-board battery for remote charging. It does NOT. I probably will return it. Another thing...the instructions are absolutely worthless.Otherwise, it works well enough as a USB charger for Nikon EN-EL15 batteries...if that is what you are looking for. And, I sure wouldn't call it super fast either.