Our Low Voltage Alarm was designed to alert an operator to a battery pack which is getting low in voltage. With an adjustable knob on top of the case the threshold voltage can be set to provide an audible and visual warning when the voltage starts to dip and it's time to change packs. As an example, if the threshold voltage is set at 11 volts, the LVA will blink green while the voltage stays above 11.5 volts. Once the voltage dips below 11.5 volts the LED will blink orange until the voltage hits the threshold setting of 11 volts at which point the LED blinks red and an audible beep initiates once every 5 seconds. This is a very useful item which can prevent a hard shutdown in the middle of that rare DX qso!