Volt Checker & Low Volt Buzzer for 1-7S Lipo/Li-ion/NiMH/LiFe (2-in-1 unit) Use for 1-7S Lipo/Li-ion/LiMn/LiFe. 1-7s Lipo Voltage Monitor & Low Volt Buzzer. Alarm shuts off when voltage of pack is restored above alarm voltage level. Two very loud alarm devices beeps and red light is on to warn you when the lipo voltage is lower than the set value. Help prevent damage to your expensive LIPO battery