Spektrum 7.4V 4000mAh 2S LiPo Transmitter Battery Overview
The 4000 2S LiPo offers long flight time, as well as advanced safety and features. It includes a built-in safety current that shuts the battery off, to avoid overcharging and damaging the battery and radio. Plus, a built-in balancing system ensures you get the longest life and power from your pack.