Spektrum 4000mAh LiPo Transmitter Battery: DX8, DX9

• Built-in cell balancer
• Built-in safety current prevents overcharging

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.