It will warn you when it is time to land your helicopter
It will Buzz with very loud BB noise when any of the cells of your battery is under 3.3V, the volume is loud enough to alert you to land your helicopter immediately to avoid accident. You can customize the voltage to alert you with very loud noise and a big red LED light.

• Small device to ensure your RC model has enough power when playing
  
• Low voltage alarm buzzer for 7.2v-14.4v lipo battery
  
• Quick test for your lipo before flight
  
• Used as inflight alarm if you are not sure the maximum flight time
  
• Small device to check the battery voltage to avoid permanent damage
• With this device, you can locate or find your lost plane/helicopter easily
  
• Within the effective range for that tracker can over 50M
  
• Simply turn off your TX, the tracer will start to scream ( just like the engines sound from the real airplane)
  
• Follow the lead and you can find your beloved plane

• When testing full power (>3.6v) 2s (7.2v) Li-Po battery 2 green LED keeping light
  
• When testing full power (>3.6v) 3s (10.8v) Li-Po battery 3 green LED keeping light
  
• When testing full power (>3.6v) 4s (14.4v) Li-Po battery 4 green LED keeping light
  
• When voltage <3.3v, it will buzzer with red LED light
• Push key and the blue LED light ,Lost Model Alarm open,when signal lost,it will buzzer.No signal within a minute action,it buzzer, then a signal action, alarm reset.
• Dimensions: 40*24*11mm
  
• Net Weight: 6.5g
  
• Battery Range: 2 To 4S Li-Po

• Connect the lost alarm between the servo (the one which runs when flying) and the receiver, i.e. act as a servo extension cord
  
• Turn on your transmitter
  
• Turn on your receiver then you will hear two beep sound
• To test if it is functioning:
  
• Do not move any of the control stick on the transmitter for 1 min. or simply turn it off
  
• You will hear a continuous beep sound after 1 minute
  
• If you cannot find you plane, do not move the control stick or turn off your transmitter for 1 min for the alarm sound
  
• By the tracking sound, you will be able to locate your RC plane / Helicopter
  
• Can be connected to any kinds of servo
  
  

• 1 x Li-Polymer Battery Low Voltage Buzzer & Lost Model Buzzer (2-4S / 2-In-1 Device)

** color of this device might be different (green or red electronic board) sometime but it is the same.

** there was a customer reported that he tested this device with a battery closed to 3.0-3.3V and this device does not work because the battery had no more power to drive this device to work. I have no idea which battery did he use but please keep in mind that a Li-Po Battery with lower than 3.7V is already risky to run out (Battery could die easily). For safety purposes, a Li-Po battery should keep in Voltage between 3.7 - 4.2V. Lower or More in voltage could damage the battery's life.