Additional peace of mind for R/C pilotsWith its compact size, the Alarmer is a "must-have" accessory for fliers everywhere. This system protects you and your model against signal potentially risky.all your work is simply plug Alarmer into one servo channel port.If no signal are detected when Rx power on, BEEP will sound and high bright LED flashing to warn of control signal inactive. Check for these possible problems should begin:Tx power turned off or batteries dischargedTx not emitting proper signal - check antenna, crystal or moduleRx not receiving proper signal - check crystal, antenna routing, etc.If a model crashes, simply turn the Tx off. Beepping and high bright LED flashing to said you in searching aircraft.