Dual Speaker Low Voltage Buzzer BB annunciator W/LED,2/3/4S Lipo battery 14.8v Dual Speaker Low Voltage Buzzer BB annunciator w/LED 2S-4S for RC Model Lipo battery Function: When testing full power(>3.6V)2S(7.2V)lipo battery 2 green LEO keeping light; When testing full power(>3.6V)3S(10.8V)lipo battery 3 green LEO keeping light; When testing full power(>3.6V)4S(14.4V)lipo battery 4 green LEO keeping light; When boltage <3.3V,it will buzzer with red LED light; Really usefull in flight if you cant see the lights. Features: Test 2S-4S lipo Battery. Small and portable low voltage alarm, with a very loud buzzer. Also has a low voltage indicator led panel. Specifications: Used for: 2S-4S lipo Battery Package size: 5 * 3 * 2cm / 2 * 1.2 * 0.8in Package weight: 8g / 0.3oz Package list: 1 * Low Voltage Buzzer BB annunciator