Is someone entering your driveway? Know in an instant with this driveway alarm! Waiting for a delivery? Want to extend your home security system? Here's your answer! This wireless system employs advanced motion detection technology to instantly alert you when someone comes up your driveway or walk. Just mount the infrared transmitter outside and put the receiver inside. When someone approaches, it sends an audible signal to alert you. Up to 400' range between transmitter and receiver. 1 '9V' and 2 'AA' batteries not included. 36 user selectable melodies/sounds.