I've been looking for alternatives to Nikon batteries and found few. This one seemed particularly interesting as it can charge more batteries than Nikon's original. Tested on my old Nikon SB900, everything works. It's a lot more than I imagined. However, it is not difficult. Build quality is decent, but I'm not sure it can last longer than Nikon's. Rarely used though as I've found that black eneloop batteries are still enough to cover a 2-3 hour session, using this only as a 'just in case' scenario.