The remote controller and receiver of the machine apply automatic matching technology, and the receiver will make sound when the batteries are installed in the receiver, then press any key of the remote controller and the receiver will make continuous sound, which shows it has successfully received the signal from the remote controller, and the remote controller may work normally. * Ideal for call or training pets * Uses vibration instead of static stimulation * 2 levels of vibrations and whistle * 150 yard range