When a battery is almost full, charging is slower to protect the battery. The trick: this hub starts charging the next battery with the remaining power.
This hub is also compatible with Phantom 4 charger (100W).
As far as I know, the device is not faster. It simply charges the 4 batteries one after the other without interruption. The only advantage of this is that you don't have to recharge 4 times and can charge all 4 overnight.