GoolRC 5Pcs 1-8S Indicator RC Li-ion Lipo Battery Tester Low Voltage Buzzer Alarm 5Pcs 1-8S Indicator RC Li-ion Lipo Battery Tester Low Voltage Buzzer Alarm Brand New & High Quality Use for 1-8s Lipo/Li-ion/LiMn/Li-Fe Protect the battery from overchare Function of checking your lipo cells voltage Voltage display function and low voltage alarm funtion