RotorLogic&reg; 1-8S LiPo Battery Voltage Meter Checker Tester with Buzzer Alarm Buzzing and flashing to warn when battery voltage too low Prrevent LiPo battery damaged due to over discharging. For 1 to 8 cells LiPo batteries from 3.7V up to 29.6V range Light weight 0.2 oz can be attached on RC helicopters