Swann DIY Wireless Gate-Open Alert Security Alarm, White (SWADS-GATEAK-GL) Easy to use, do-it-yourself wireless alert system notifies you if a gate or door opens for home or business security Connect in minutes with easy mounting, pairing & convenient wireless operation (uses 3 x AA batteries for Receiver & 3 x AAA batteries for Sensor - batteries not included) Position the Gate Alert & its 2 magnetic sensors on a door or gate, & if the sensors are separated a siren will trigger on the Gate Alert & on the Receiver Unit indoors perfect for notifying you if children have opened a gate to a swimming pool area, street, etc with a delay switch to allow adults to open & close the gate within 7 seconds without triggering the siren The Receiver unit emits an audible alarm & lights up when the Gate Alert Sensors detect movement