MAD CATZ Wii Battery Pak for the Wii Fit

Compact and durable set the battery charging cable for the Wii Balance Board. With this solution, you no longer need expensive batteries. Only remove the batteries from your Wii Balance Board and replace it with this kit for up to 20 hours of continuous play. The included USB cable allows charging without removing the battery.
Specifications:
Battery life up to 20 hours
Charging without removing batteries
Charge from a USB port or PC Nintendo Wii