With the Rozemeijer USB Lithium Battery Charger, you charge the LIR425 (2 included) so you always have power for your Pike and/or Dart Floats with Light. Additionally, you can purchase the LIR425 separately should you wish to fish with multiple floats. The USB charger features 4 slots: 2 for charging and 2 for storing the batteries so you don't lose them. Thanks to the USB capability, you can even charge your floats in your car while on your way to your fishing spot if you want to be sure of having enough power. Or how about using a power bank? In short, you will never run out of power for your Pike and/or Dart Floats with Light with this USB charger and LIR425 batteries. Insert the LIR425 into the opening marked with a 'lightning bolt' symbol to charge, and once they are full, insert them into the opening marked with a 'full battery' symbol. The charger will light up green while the batteries are charging.