... customized 4.Factory service&pri wireless remote key finder/electronic key finder/key finder with keychainOne card matches 4 receivers, ... will beep constantly(Dee...dee...),and push the button'A'on the card,keychain will stop beep ... ,Then turn on the 2nd keychain,and push button'B',and the same for the rest 2 ... to find the lost keys,push the corresponding button on the card,and the keychain will sound ...