This in-line voltage, low level detector seats between 2-6S Lipo Battery and ESC. It allows you to select the voltage level from 3.4V to 3.7V which will warn you by loud buzzer and flashing all 4 LEDs when the voltage levels drops below the level you set up. To select the desired low voltage level just press and hold down the button until it starts flashing then you can select voltage and wait until it stops flashing

Specifiactions:

Size: 56 x 21 x 20mm

Weight: 21g