This product enables you to understand lithium batteries by automatically detecting and displaying the voltage of each cell and the total voltage of lithium batteries, ranging from 1S to 8S. It supports reverse connection protection. When the voltage value falls below the set buzzer alarm level, the buzzer will sound. Additionally, the bright red LED is set to 3.3V by default according to the factory settings, but you can change it by pressing the voltage adjustment button if desired.