Readytosky RC 1-8s Lipo Battery Tester Monitor Low Voltage Buzzer Alarm Voltage Checker with LED Indicator for Lipo Life LiMn Li-ion Battery(4PCS) Easy to use - works with any 1-8s lipo/li-ion/limn/li-fe rc drone battery. Small Size - 1.57*0.91*0.43 Inch, Weight: 10g/1pc. Super loud - Sound intensity:110dB, Range:50m(Affected by the external environment). Just plug into the balance plug, the LED will cycle through the individual cell voltages as well as list the total voltage. Display Mode: Battery cell voltages, total voltages, lowest cell voltage, Remaining battery capacity. Use for 1-8S Lipo/Li-ion/LiMn/Li-Fe Voltage detection precision: +_0.01V. Unit voltage display range: 0.5~4.5V Total voltage display range: 0.5~36V 1S test mode voltage range: 3.7~30V Low voltage alarm mode for 2-8S Alarm set value range:OFF~2.7~3.8V Size: 40mm x 25mm x 11mm Weight: 9g Easy to use - works with any 1-8S Lipo/Li-Ion/LiMn/Li-Fe RC drone battery. Protect the battery from overcharging and overdischarging. Super loud alarm sound makes it easier to find your drone.