... you want to find. LED--It will show a red light when the signal is sending out. Buttons--3 ... 1st keychain's switch to ON position,it will beep constantly("dee...dee..."),and push the button"A",LED on, ... LED off,Then turn on the 2nd keychain,and push button"B",keychain will stop beep after match,LED ... you want to find the lost keys,just push the corresponding button on the card,and the keychain will sound ...