With this device, you can easily locate and find your lost plane/helicopter
  ,The effective range for this tracer is over 50 meters.Simply turn off your
  TX, the tracer will start to scream (just like the engine sound of the real
  airplane)You can find your beloved plane by following the lead
  Suitable for All PPM/FM, PCM/FM, AM Tx/Rx
  Weight : 4.7g only
  Operating Voltage : 4-6 volts DC
  Current consumption : < 35 mA (1 mA at standby mode)
  Alert Level : 85dB ( like jet-plane engines sound)
  Installation : Share signal channel from any Servo unit

Instructions:

  Connect the alarm between the servo and the receiver, i.e. act as a servo

  extension cord

  Turn on your TX. and you will hear 2 beep sound

  Do not move any of the control stick on the TX or simply turn off the the TX.

  You will hear a continuous beep sound after 1 minute.

  It will stop once you turn on your TX or move the control stick

  If you ignore the continuous beep sound for around 2minutes, the beep sound

  will change to a louder V sound

  You need to disconnect the alarm from the receiver in order to switch off the

  alarm.