The Hobbyking 2-8S Cell Checker with Low Voltage Alarm features loud twin Piezo alarms to notify you once your cells reach a user defined voltage. You can customize the alarm to sound at a voltage between 2.7v~3.8v Per cell in 0.10v increments by pressing the setting mode button. This unit also features a handy built in LED display that will show the voltage of each cell followed by the over all voltage of the pack. Don’t risk your model by flying on depleted batteries, at this price piece of mind flying cant be any cheaper! Specifications. Input: 2~8S Battery type: Lipo/LiFe/Li-ion Cell Voltage Display Range: 0.5v~4.5v Total Voltage Display Range: 3.7~36v Alarm set values: Off or 2.7~3.8v Size: 41x30x13mm Weight: 13g(with case)