Skylink HA-434TL  Long Range Household Alert & Alarm Home Garage Driveway Business Office Security Protection Indoor Outdoor Infrared Motion Detector Sensor Accessory NO MONTHLY FEES and easy DIY (Do It Yourself) installation Add-on/extra sensor, compatible with Skylink Long Range Household Alert & Alarm Systems (Requires HA-434RL receiver to work) Motion detecting range up to 40 feet. operating range from the receiver to the motion sensor is up to 800 feet in open area. - BATTERY POWERED with low battery indication: be informed when the sensor`s battery is low before it stops sending signals. Battery not included. One HA-434RL Household Alert Receiver (AC/DC adapter included) & Two HA-434TL Indoor/Outdoor Motion Sensor (Battery not included)