Description:
Turn up the receiver's switch to "on" position, it will beep constantly('dee...dee...'), and push one button on the transmitter, the receiver will stop beep after matching.
When you want to find the lost keys or other things, just press the matching button on the transmitter, and the receiver will sound alarm within 0.5-2 seconds(according to the distance), the alarm will last for 4 seconds and then stop.

Specifications:
External material: plastic
Design: RF Wireless Technology
Transmitter&receiver powered by button cell batteries(included)
Size: Receiver: 4.5 x 2.8 x 1.1cm
       Transmitter: 6 x 3.2 x 1.1cm

Package included:  
1 x Transmitter
4 x  Receiver