Hooshion Low Voltage Buzzer 1-8S Lipo Battery Voltage Tester Low Voltage Buzzer Alarm Electric Display 1-8S the latest two in one electric quantity display /BB ring low voltage (adjustable) alarm / double function A product has two functions, voltage display and low pressure alarm (low voltage adjustable) Support reverse connectionprotection. you can know you whenever and wherever possible the operating state of the battery, thebattery will not because you have to put or overcharge damage. weight: 9g