Intellect LiFe battery.

2100mAh
2S
RX connector.
17.5*42.5*79mm
103g

LiFe batteries have nominal 3.3v per cell. They have the advantage of providing a flatter discharge curve and longer cycle life compared to LiPo batteries. They are considered safer that LiPo batteries due to their chemistry.

Ensure your charger is set to LiFe mode when charging.