Extra Door / Window Sensor... SAVE! Protects entrances and sends a signal to the control panel or dialer when contact is broke. Up to 100' range. Measures 3 3/8 x 1 1/2 x 1 1/8" and weighs 2 3/5 ozs. Order ONLINE Today! AVAILABLE SEPARATELY: Skylink Complete Wireless Alarm System and Smoke / Carbon Monoxide or Extra Motion Sensors - word search in our Store for 'Sensors' and 'Alarm System'. Extra Door / Window Sensor