LEGO Power Functions Rechargeable Battery Box 8878
This rechargeable battery box has built-in Lithium polymer batteries for low weight and maximum power. Use it in your LEGO Power Functions models and never have to use disposable batteries again! Use the #8887 10VDC LEGO Transformer to charge the battery! Motor speed can be controlled via the battery box speed control dial! Output voltage is 7.4 V!