When the voltage is lower than the set value, it will beep with a red LED light, preset value 3.3V. Lipo battery voltage tester 1-8s, low voltage alarm mode for 2-8S, check your Lipo cell voltage function Voltage display function and low voltage alarm function (Note: When the voltage is lower than the alarm value, it will always sound. And when the measured product is unplugged, the alarm will stop.) A very loud alarm sound makes it easier to find your drone. Display Mode: battery cell voltages, total voltages, lowest cell voltage, remaining battery capacity. Specification: Voltage detection accuracy: +_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 setting value range: OFF ~ 2.7 ~ 3.8V Protect the battery from overcharging or over-discharging. Use for 1-8s Lipo / Li-ion / LiMn / Li-Fe. Test the working status of the lithium battery. Automatic reverse connection protection. Color: black Material: plastic Package Contents: 8 x 2 in 1 1-8s RC Battery Tester Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.