Manufacturer's Description

Make sure your Balance Board doesn't run out of energy beefore you do!
Say goodbye to expensive batteries with the Mad Catz Rechargeable Battery Pak for the Wii Fit Balance Board. Simply remove the battery cover and batteries from your Balance Board and replace them with the Battery Pack for up to 20 hours of continuous energy. The included USB charge cable - compatible with the Wii and PCs - makes recharging the internal batteries easy and convenient.
* Eliminates the need to purchase costly batteries
* Provides up to 20 hours of gameplay
* Charges via USB - Wii or PC