I had this clarified briefly by our supplier. The 6.4 volt 900 mAh battery does not fit the Mini Mario Copter, this is intended for RC vehicles. It doesn't fit in terms of size and is about twice as heavy as the drone itself. According to the supplier, the following battery fits, but I can't find it in our range: "Battery 3.7 Volt 430 mAh 410379"