Spektrum 4000mah 2S 7.4v LiPo Transmitter Battery suit DX8, DX9

The 4000 2S LiPo offers not only double the flight time as the stock DX8 battery but also advanced safety and features. It also 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 to make sure you get the longest life and power from your pack.