LIPO Low Voltage Alarm and Voltage Battery checker
Must have for LiPo batteries.
Once the battery is below a preset level (usually 3.6V per cell) this will emit a loud and annoying beep to tell you the battery is low.
LiPo batteries will get damaged (and puffy) when over dis-charged. Use this LiPo alarm to prevent damage.
Also doubles are as a battery indicator.