This is the LiFe 2S 6.6V 850mAh 10C UNI Receiver Plug by Venom.
When you want a powerful battery pack that you can depend on even when you push it to its limits, this Venom 10C 2S 850mAh 6.6V LiFe Receiver gives you similar voltage to traditional AA RX/TX applications with the extended battery LiFe and sustainability of lithium batteries. Whether you have a short course truck, buggy, monster truck, heli, jet, airplane, drone, or quad, this battery pack delivers the results and run-time you have come to expect from all Venom batteries. With features such as premium 22 AWG soft silicone wire leads this battery gives you the reliable power you are looking for. A perfect fit for many transmitter and receiver applications.